Dynamoelectric machine having an encapsulated coil structure

ABSTRACT

Magnet wires wound in slots in a lamination stack of a dynamoelectric machine are encapsulated, in whole or in part, with plastic. The plastic may be thermally conductive and have features molded therein that enhance heat transfer. The plastic may stiffen the armature and increase its critical speed. Characteristics of the plastic, its geometry and its distribution may be varied to adjust spinning inertia and resonant frequency of the armature. The magnet wires may be compressed into the slots, by application of iso-static pressure or by the pressure of the plastic being molded around them. Larger magnet wire can then be used which increases the power of the electric motor using the armature having the larger magnet wire. A two or three plate mold may be used to mold the plastic around the armature. Balancing features can be molded in place. The plastic can have a base polymer that is a blend of two or more polymers and various thermally conductive fillings.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/365,065 filed on Feb. 12, 2003, which is adivisional of U.S. patent application Ser. No. 09/836,517 filed on Apr.17, 2001, which is a continuation-in-part of U.S. patent applicationSer. No. 09/756,959 filed Jan. 9, 2001. This application claims thebenefit of U.S. Provisional Application No. 60/395,251 filed on Jul. 12,2002.

TECHNICAL FIELD

[0002] This invention relates to dynamoelectric machines, and moreparticularly to a dynamoelectric machine having a coil structureencapsulated with a thermally conductive plastic.

BACKGROUND OF THE INVENTION

[0003] Dynamoelectric machines are machines that generate electric poweror use electric power. Common types of dynamoelectric machines arealternators, generators, and electric motors.

[0004] Electric motors are used in a wide variety of applicationsinvolving power tools such as drills, saws, sanding and grindingdevices, yard tools such as edgers and trimmers, just to name a few suchtools. These devices all make use of electric motors having an armatureand a field, such as a stator. The armature is typically formed from alamination stack or core around which a plurality of windings of magnetwires are wound. The lamination stack is formed to have a plurality ofpoles around which the magnet wires are wound. In this regard, thelamination stack may be formed with a plurality of slots in which themagnet wires are wound. Insulators are typically provided between themagnet wires and the lamination stack. Magnet wires, as that term iscommonly understood, are wires of the type conventionally used to windcoils in electric machines, such as armatures and stators. The magnetwires are coupled at their ends to a commutator, such as to tangs whenthe commutator is a tang type commutator, disposed on an armature shaftextending coaxially through the lamination stack.

[0005] The stator is also typically formed from a lamination stackaround which a plurality of windings of magnet wires are wound. The endsof the magnet wires typically have terminals affixed that are thencoupled to a source of electrical power. The lamination stack is formedto have a plurality of poles around which the magnet wires are wound. Inthis regard, the lamination stack may be formed with a plurality ofslots in which the magnet wires are wound. Insulators are typicallyprovided between the magnet wires and the lamination stack.

[0006] In the manufacturing process for the armature described above,once the magnet wires have been secured to the commutator, a “trickle”resin is applied over the magnet wires and over the ends of the magnetwires where they attach to tangs associated with the commutator. Theprocess of applying the trickle resin is a somewhat difficult process tomanage to obtain consistent results. It also has a number of drawbacks,not the least of which is the cost and difficulty of performing it withreliable, consistent results.

[0007] Initially, the trickle process requires the use of a relativelylarge and expensive oven to carefully preheat the partially assembledarmatures to relatively precise temperatures before the trickle resincan be applied. The temperature of the trickle resin also needs to becarefully controlled to achieve satisfactory flow of the resin throughthe slots in the lamination stack of the armature. It has proven to beextremely difficult to achieve consistent, complete flow of the trickleresin through the slots in the lamination stack. As such, it isdifficult to achieve good flow inbetween the magnet wires with thetrickle resin. A cooling period must then be allowed during which air istypically forced over the armatures to cool them before the nextmanufacturing step is taken. Further complicating the manufacturingprocess is that the trickle resin typically has a short shelf life, andtherefore must be used within a relatively short period of time. Themanufacturing process for making wound stators may involve a similartrickle resin process.

[0008] Referring to FIG. 1, there is illustrated a prior art armature 10made in accordance with a conventional manufacturing processincorporating the trickle resin application steps describedhereinbefore. The armature 10 incorporates a lamination stack 12 havinga plurality of longitudinal slots 14 disposed circumferentiallytherearound. Wound within the slots 14 is a large plurality of magnetwires 16 forming coils. An armature shaft 18 extends coaxially throughthe lamination stack 12 and includes a commutator 20. An independentlyformed plastic fan 22 is secured, typically by adhesives, to thelamination stack 12. The fan 22 typically includes a plurality of legs24 which project into the slots 14, thus taking up space which wouldmore preferably be occupied by the magnet wires 16. Trickle resin 26 isapplied over the magnet wires 16, in the slots 14, and also at the tangs25 where the ends 16 a of the magnet wires 16 attach to the commutator20.

[0009] Abrasive particles are drawn in and over the armature by thearmature's fan, particularly when the armature is used in tools such asgrinders and sanders. As shown particularly in FIG. 2, the air flow,shown by arrows 30, impinges magnet wires 16 of end coils 17 (theportion of the coils of magnet wires that extend around the ends of thelamination stack 12 between the slots 14 in the lamination stack 12).The air flow 30 contains abrasive particles and the impingement of theseabrasive particles on magnet wires 16 can wear away the insulation ofmagnet wires 16.

[0010] With present day manufacturing techniques, an additional orsecondary operation is often required to protect the armature (andspecifically the magnet wires) from the abrasive particles. Suchsecondary operations include a coating of higher viscosity trickleresin, an epoxy coating, or wrapping the wires, such as with cotton,string or the like. This serves to further increase the manufacturingcost and complexity of the armature.

[0011] Still another drawback with the trickle process is the relativelyhigh number of armatures which are often rejected because of problemsencountered during the process of applying the trickle resin to anotherwise properly constructed armature. Such problems can includecontamination of the commutator of the armature by the trickle resinduring the application process, as well as uneven flow of the trickleresin if the pump supplying the resin becomes momentarily clogged.Accordingly, the difficulty in controlling the trickle resin applicationprocess produces a relatively large scrap rate which further adds to themanufacturing cost of electric motors.

[0012] Slot insulators and end spiders of armatures have been formed byinsert molding the armature shaft and lamination stack in plastic. FIG.3 shows such a prior art armature 40 having a lamination stack 42 on ashaft 44. Lamination stack 42 has a plurality of slots 46. The plasticis molded underneath the lamination stack 42 and around shaft 44 toinsulate the shaft 44 from the lamination stack 42. The plastic is alsomolded to form end spiders 48 and molded in slots 46 to form slot liners50. Slot liners 50 insulate the windings 52 from lamination stack 42after the windings 52 have been wound in the slots 46 to form coils 54.

[0013] The plastic used in molding the prior art armature 40 has beenplastic that is not thermally conductive, such as nylon or PPS. This canresult in problems in dissipating the heat generated in the coils 54during the operation of the motor in which armature 40 is used.

[0014] Most armatures or rotors used in dynamoelectric machines, such asmotors and generators, are dynamically balanced to reduce the vibrationforce transmitted to the motor housing by way of the bearings. Dynamicbalancing requires that material be added to or removed from the ends ofthe armature. The most beneficial places to do this are on planes nearto the bearing planes at the largest possible radius. However, forpractical reasons, universal motor armatures and permanent magnet motorarmatures are usually balanced by selectively removing material from thesurface of the iron core (also called the lamination stack).

[0015] This balancing process has a number of disadvantages. First, theplanes in which the material are removed are located within the lengthof the lamination stack and thus are relatively distant from the bearingplanes where the imbalance forces are transmitted to the rest of theproduct. Second, removal of material from the motor's active iron core(lamination stack) has a negative effect on performance, particularly,torque ripple. Third, balancing by removing material from the surface ofthe lamination stack requires that the tooth tops of the laminationstack be thicker than needed for spreading magnetic flux. The thickertooth tops rob winding space from the slots in the lamination stack inwhich magnet wires are wound. Fourth, the surface of the laminationstack is not homogenous. It consists of iron at the tooth tops and airor resin in the winding slot area. This non-homogeneity presents a moredifficult computation to the dynamic balancing machine that must decidehow much material to remove and where to remove it from. Consequently,the dynamic balance machines often must make repetitive correctivepasses during which even more iron is removed from the lamination stack,further reducing performance.

[0016] Coil stays have typically been used to hold the magnet wires,such as magnet wires 16, in the slots, such as slots 14, in thelamination stack, such as lamination stack 12. FIG. 4 shows one of slots14 of lamination stack 12 of prior art armature 10 (FIG. 1) disposedbetween opposed poles 13 of lamination stack 12 and magnet wires 16wound in slot 14. A slot liner 15, typically made of a paper insulation,is disposed in slot 14 between the magnet wires 16 and walls oflamination stack 12. Magnet wires 16 are retained in slot 14 by a coilstay 19, which is illustratively made of vulcanized fibers that are bothelectrically and thermally insulative. Such prior art coil stays havecertain undesirable characteristics. First, they occupy space that couldotherwise be filled with magnet wires 16. Second, the poor thermalconductivity of the coil stay material limits the amount of heat thatcan be transferred to the surface of lamination stack 12.

[0017] As is known, the power of a motor having magnet wires wound inslots of a lamination stack is a function of the current flowing throughthe magnet wires and the number of turns of magnet wires. A motor havinga given output, i.e., {fraction (1/10)} horsepower, ⅛ horsepower, ¼horsepower, requires that a certain number of turns of magnet wires thatcan carry a given current be used. The ability of the magnet wires tocarry the given current is a function of the size (diameter) of magnetwires. The size of the magnet wires that must be used to wind the givennumber of turns of the magnet wires in turn dictates the size of theslots in which they are wound. That is, the slots must be large enoughto hold the required number of turns of magnet wires.

[0018] If a larger size magnet wire can be used to wind the magnetwires, higher power can be achieved due to the decreased resistance ofthe larger size magnet wire compared with the smaller size magnet wire.However, using a larger size magnet wire to wind the magnet wires wouldtypically require larger slots to accommodate the required number ofturns of the larger size magnet wire, which in turn would require alarger lamination stack. Thus the armature would be larger.

[0019] Mains driven power tools, tools driven from power mains such as120 VAC, are often double-insulated to protect the user from electricshock. Double-insulation requires two separate levels of electricalinsulation: functional insulation and protective insulation. Functionalinsulation electrically insulates conductors from one another and fromnon-touchable dead-metal parts of the armature. An example of anon-touchable dead metal part is the lamination stack of the armature,such as lamination stack 12 (FIG. 1). The functional insulation systemincludes the core insulation, magnet wire film, and the resin matrixthat bonds the whole together. Core insulation could also consist ofepoxy coatings applied by a powder coating process.

[0020] The protective insulation consists of an electrically insulativetube or sleeve disposed between the touchable dead-metal shaft, such asshaft 18 (FIG. 1), and the rest of the armature structure. The shaft isconsidered touchable since it is in conductive contact with exposedconductive parts of the tool, such as a metal gearbox and/or metalspindle or chuck. In order to provide protection at the end of thetool's functional life due to abusive loads and burnout, the protectiveinsulation barrier must have electrical, thermal, and structuralproperties that are superior to those of the functional insulationsystem. Therefore, the insulating tube or sleeve is usually constructedof high-temperature, glass reinforced thermosetting resin. Othermaterials such as ceramic, mica, and composites of these material couldalso be used to make the insulating tube or sleeve.

SUMMARY OF THE INVENTION

[0021] In an aspect of the invention, an armature for an electric motorhas an armature shaft having a lamination stack thereon. The armatureshaft and lamination stack are insert molded in thermally conductiveplastic. In an aspect of the invention, the plastic increases stiffnessand thus increases the critical speed of the armature. In an aspect ofthe invention, the mass of plastic, its distribution, or both are variedto adjust the spinning inertia of the armature. In another aspect of theinvention, the geometry of the plastic, it mechanical properties, orboth are varied to adjust the resonant frequency (critical speed) of thearmature.

[0022] In another aspect of the invention, bondable wire (which is wirethat has a layer of heat activated adhesive thereon) is used to wind thecoils of a coil structure for a dynamoelectric machine, such as anarmature for an electric motor or a stator for an electric motor.Plastic, preferably thermally conductive plastic, is molded around thebondable wire. The heat of the plastic as it is being molded activatesthe heat activated adhesive on the bondable wire, bonding the wirestogether.

[0023] In another aspect of the invention, a coil structure for adynamoelectric machine has wires wound in slots in a lamination stackforming coils. Thermally conductive plastic is molded around the wiresat a pressure to at least partially deform the wires into polygonalshapes. The polygonal shapes increase the contact surface area of thewires and enhance heat transfer from the wires.

[0024] In another aspect of the invention, the pressure at which thethermally conductive plastic is molded around the wires is set at apressure that compacts the wires in the slots in the lamination stackthat allows for increased slot fill.

[0025] In an aspect of the invention, increased power is achieved byusing a larger size magnet wire. The pressure of the plastic beingmolded is set to compact the magnet wires so that the same number ofturns of magnet wires wound with the larger size magnet wire can beused. The larger size magnet wire has a lower resistance per givenlength compared with the smaller magnet wires heretofore used for agiven size of motor which results in increased power when the samenumber of turns of magnet wires wound with the larger size magnet wireare used. In a variation of this aspect of the invention, iso-staticpressure is used to compact the magnet wires in the slots.

[0026] In another aspect of the invention, the plastic is molded aroundarmature lead wires, the portion of the magnet wires leading to thecommutator, and provides support for the armature lead wires.

[0027] In another aspect of the invention, thermally conductive plasticis molded around at least a portion of the magnet wires of an armatureto at least partially encase them. In an aspect of the invention, thethermally conductive plastic has thermally conductive additives such asaluminum oxide, boron nitride, or aluminum nitride. In an aspect of theinvention, the thermally conductive plastic has phase change additivestherein. In an aspect of the invention, the plastic can have a basepolymer that is Nylon, PPS, PPA, LCP, or blends.

[0028] In another aspect of the invention, the plastic can be athermoset and in addition to injection molding, transfer molding orcompression molding used to mold the plastic around the armature.

[0029] In another aspect of the invention, a coil structure for adynamoelectric machine has a lamination stack with a plurality of slotstherein. The slots are lined with slot liners formed of thermallyconductive plastic. Wires are wound in the slots to form coils. The slotliners enhance heat transfer out of the wires and also electricallyinsulate the wires from the lamination stack. In an aspect of theinvention, thermally conductive plastic is molded to form the slotliners. In an aspect of the invention, the coil structure is an armaturefor an electric motor and the thermally conductive plastic is alsomolded to form end spiders and to be disposed between the armature shaftand lamination stack, electrically insulating the lamination stack fromthe armature shaft.

[0030] In another aspect of the invention, an armature for an electricmotor has a lamination stack on a shaft with a tang type commutatormounted on one end of the shaft. The lamination stack has slots in whichmagnet wires are wound forming coils. Ends of the magnet wires areattached to tangs of the commutator. The commutator has a commutatorring divided into a plurality of segments with slots between thesegments. The commutator is notched around an axial inner end with thenotches located where axial inner ends of the slots will be once theslots are cut. The notches are filled with plastic when the commutatoris made by molding a core of plastic, such as phenolic, in thecommutator ring before the commutator ring is mounted on the armatureshaft. The slots are then cut in the commutator ring to divide it intosegments. The slots are cut axially through the commutator ring and runfrom an axial distal end of the commutator ring part way into thenotches at the axial inner end of the commutator ring. The magnet wires,commutator and armature shaft are at least partially encapsulated inplastic, such as by insert molding. The mold used to mold the plasticincludes projections that extend between the tangs of the commutator andagainst the notches filled with plastic. The notches filled with plasticand the projections of the mold prevent plastic flash from getting intothe slots of the commutator ring when plastic is molded to at leastpartially encapsulate the magnet wires, armature shaft, and commutator.

[0031] In another aspect of the invention, an armature for an electricmotor has a lamination stack on a shaft with a stuffer type commutatormounted on one end of the shaft. The stuffer commutator has a commutatorring divided into a plurality of segments by slots between the segments.Insulative inserts extend part way into each slot from an axial innerend of the commutator ring. Axial inner ends of each segment have slotsinto which ends of magnet wires are pressed. The lamination stack hasslots in which the magnet wires are wound forming coils. The magnetwires, commutator and armature shaft are at least partially encapsulatedin plastic, such as by insert molding. The mold used to mold the plastichas a portion that seals around the inner end of the commutator ringabove the inserts to prevent plastic flash from getting into the slotsbetween the segments of the commutator ring when the magnet wires,armature shaft and commutator are at least partially encapsulated withplastic.

[0032] In another aspect of the invention, an armature having alamination stack with slots therein is at least partially encapsulatedby molding thermally conductive plastic around at least parts of it,including in the slots in the lamination stack and around magnet wireswound in the slots. The plastic is molded in the slots so that the slotsare cored out leaving recesses in the slots between teeth of thelamination stack. The recesses reduce the amount of plastic molded,enhance heat transfer, and provide slots for receiving projections oftools used in processing the armature to properly locate and orient thearmature.

[0033] In another aspect of the invention, a coil structure for adynamoelectric machine has a lamination stack with a plurality of slotstherein. Magnet wires are wound in the slots to form coils. Thermallyconductive plastic is molded around the magnet wires to at leastpartially encapsulate them. Features, such as fins, texturing, or bothare formed in the surface of the thermally conductive plastic to enhanceheat transfer. In an aspect of the invention, the features aremetallized. In an aspect of the invention, the features are pre-formedand insert molded when plastic is molded around the magnet wires. In anaspect of the invention, the features include a metallic finned cap thatfits over the end coils of the magnet wires.

[0034] In an aspect of the invention, elements requiring physicalrobustness, such as the fan, are pre-formed of higher strength materialand insert molded when plastic is molded around the armature toencapsulate it in whole or in part.

[0035] In another aspect of the invention, the armature is completelyencapsulated with plastic and excess plastic machined off.

[0036] In another aspect of the invention, the armature is a doubleinsulated armature that is encapsulated, in whole or in part, withplastic. In an aspect of the invention, the double insulated armaturehas an insulative sleeve that is disposed between a shaft of thearmature and a lamination stack and between the shaft and a commutator.In an aspect of the invention, the insulative sleeve is disposed betweenthe shaft of the armature and the lamination stack and extends up to thecommutator with a seal disposed between the commutator and theinsulative sleeve to prevent any plastic from getting into any gapbetween the insulative sleeve and the commutator when plastic is moldedaround the armature.

[0037] In another aspect of the invention, the armature is a doubleinsulated armature having a commutator and lamination stack mounteddirectly on an internal shaft. The internal shaft is coupled to anexternal pinion and bearing journal by means of an insulated barrier.

[0038] In another aspect of the invention, the plastic molded around thelamination stack, portions of the commutator and the armature shafthelps holds the commutator and lamination stack on the armature shaftand provides for improved torque twist. In a variation of this aspect ofthe invention, the armature shaft is provided with features, such as oneor more flats, that interlock with the plastic molded around them tofurther improve torque twist.

[0039] In an aspect of the invention, a three plate mold is used to moldthe plastic around the armature. In a variation, a two-plate mold isused that has overflow tab cavities into which plastic flows beforeflashing over the commutator of the armature around which plastic isbeing molded.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The various advantages of the present invention will becomeapparent to one skilled in the art by reading the followingspecification and subjoined claims and by referencing the followingdrawings in which:

[0041]FIG. 1 is a side elevation view of a prior art armature whichincorporates the conventional trickle resin coating and separatelymanufactured fan secured by adhesives to the armature;

[0042]FIG. 2 is a schematic view of air flow around end coils of a priorart armature;

[0043]FIG. 3 is a perspective view of a prior art armature with plasticmolded in slots in a lamination stack to form slot liners, at the endsof the lamination stack to form end spiders and around a shaft of thearmature;

[0044]FIG. 4 is a side view of a section of a slot in a lamination stackof a prior art armature with magnet wires held therein by a coil stay;

[0045]FIG. 5 is a side elevation view of an armature in accordance withan aspect of the invention;

[0046]FIG. 6 is a side elevation view of an armature in accordance withan aspect of the invention;

[0047]FIG. 7 is an end view of the armature of FIG. 6;

[0048]FIG. 8 is an end view of a variation of the invention shown inFIGS. 6 and 7;

[0049]FIG. 9 is a coil stay in accordance with an aspect of theinvention;

[0050]FIG. 10 is a view of a section of a slot in a lamination stackwith bondable magnet wires therein with the heat activated adhesive ofthe bondable magnet wires having been activated by the heat of plasticas it is molded in accordance with an aspect of the invention;

[0051]FIG. 11 is a view of a section of a slot in a lamination stackwith magnet wires therein deformed by pressure of plastic molded aroundthem in accordance with an aspect of the invention;

[0052]FIG. 12 is a view of a section of a slot in a prior art laminationstack with magnet wires therein;

[0053]FIG. 13 is a view of a section of a slot in a lamination stackwith larger size magnet wires therein in accordance with an aspect ofthe invention;

[0054]FIG. 14 is a view of a section of a slot in a lamination stack inwhich magnet wires are compressed by iso-static pressure;

[0055]FIG. 15 is a view of a section of a stator for an electric motorencapsulated with a thermally conductive plastic in accordance with anaspect of the invention;

[0056]FIG. 16 is an end view of a section of a stator with a thermallyconductive plastic molded in slots in a lamination stack to form slotliners in accordance with an aspect of the invention;

[0057]FIG. 17 is a perspective view of an armature with a tang typecommutator made so that plastic flash is prevented from getting in slotsbetween segments of the commutator in accordance with an aspect of theinvention;

[0058]FIG. 18 is a perspective view of a tang type commutator;

[0059]FIG. 19 is a view of a mold, shown representatively, used inmaking the armature of FIG. 8;

[0060]FIG. 20 is a perspective view of an armature with a stuffer typecommutator made so that plastic flash is prevented from getting in slotsbetween segments of the commutator in accordance with an aspect of theinvention;

[0061]FIG. 21 is a section view of a partial section of the armature ofFIG. 11 taken along the line 21-21 of FIG. 20;

[0062]FIG. 22 is a perspective view of an armature encapsulated with athermally conductive plastic with features for enhancing heat transferin accordance with an aspect of the invention;

[0063]FIG. 23 is a perspective view of another armature encapsulatedwith a thermally conductive plastic with features for enhancing heattransfer in accordance with an aspect of the invention;

[0064]FIG. 24 is a perspective view of an armature encapsulated with athermally conductive plastic with a necked down region adjacent thecommutator in accordance with an aspect of the invention;

[0065]FIG. 25 is a perspective view of an armature having features forheat transfer in accordance with an aspect of the invention;

[0066]FIG. 26 is a side view of features of the armature of FIG. 25formed in accordance with an aspect of the invention;

[0067]FIG. 27 is a side view of features of the armature of FIG. 25formed in accordance with an aspect of the invention;

[0068]FIG. 28 is a side section view, broken away, of an armature shafthaving features that interlock with plastic molded around them inaccordance with an aspect of the invention to improve twist torque;

[0069]FIG. 29 is a perspective view of a double insulated armature inaccordance with an aspect of the invention;

[0070]FIG. 30 is a perspective view of another double insulated armaturein accordance with an aspect of the invention;

[0071]FIG. 31 is a perspective view of another double insulated armaturein accordance with an aspect of the invention;

[0072]FIG. 32 is a side section view of a three plate mold used toencapsulate an armature in accordance with the invention;

[0073]FIG. 33 is a top view of the three plate old of FIG. 32;

[0074]FIG. 34 is a perspective view of a portion of an armature moldedin the three plate mold of FIG. 32 opposite an end of the armature onwhich a commutator is affixed;

[0075]FIG. 35 is a perspective view of a portion of an armature moldedin the three plate mold of FIG. 32 adjacent a commutator;

[0076]FIG. 36 is a portion of a section view of the three plate mold ofFIG. 32 and a portion of a lamination stack being encapsulated; and

[0077]FIG. 37 is a representative view of a two-plate mold havingoverflow tab cavities in accordance with an aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0078] Referring now to FIG. 5, a motor 100 in accordance with apreferred embodiment of the present invention is disclosed. The motor100 includes an armature 102 and a stator 104, the stator beingillustrated in highly simplified fashion. The armature 102 incorporatesa lamination stack 106 having a plurality of longitudinal slots 108arranged circumferentially therearound. A plurality of magnet wires 110are wound in the slots 108 to form a plurality of coil windings havingend coils 117. An armature shaft 112 extends coaxially through thelamination stack 106 and has disposed on one end thereof a commutator114. A thermally conductive plastic 116 is injection molded over thearmature 102 so that the plastic flows into and through each of theslots 108. The thermally conductive plastic 116 is applied by placingthe armature 102 in a suitable injection molding tool and then injectingthe thermally conductive plastic 116 under a suitably high pressure intothe molding tool. The thermally conductive plastic 116 preferably atleast partially encases the magnet wires 110, and more preferablycompletely encases the magnet wires to form an excellent means fortransferring heat therefrom. The plastic 116 also encases the ends 118of armature lead wires 119 of the magnet wires 110 which are secured totangs 120 operably associated with the commutator 114.

[0079] A fan 122 is also integrally formed during the molding of thethermally conductive plastic 116 at one end of the lamination stack 106.Forming the fan 122 as an integral portion of the thermally conductiveplastic 116 serves to completely eliminate the manufacturing steps inwhich a trickle resin is applied to the lamination stack 106 and then aseparately formed fan is adhered to the lamination stack 106.

[0080] The molding of the thermally conductive plastic 116 tosubstantially or completely encase the magnet wires 110 serves toefficiently conduct heat away from the magnet wires. Thus, the thermallyconductive plastic 116 even more efficiently serves to secure the magnetwires 110 to the lamination stack 106 to prevent movement of the wires,as well as to secure the magnet wires to the tangs 120 and to improvethe conduction of heat from the wires.

[0081] The molding of the fan 122 as an integral portion of thethermally conductive plastic coating 116 also provides a significantmanufacturing benefit by removing the cost associated with separatelyforming such a fan component and then securing the component via anadhesive to the lamination stack 106. This allows the fan 122 to beconstructed even more compactly against the lamination stack 106 whichallows a motor to be constructed which requires less space thanpreviously developed motors employing independently formed fans.

[0082] Another advantage of having the fan 122 molded from the thermallyconductive plastic is that the fan will be even more resistant to hightemperatures which might be encountered during use which stresses themotor 100. With previously developed motors, the fan mounted to thearmature thereof is often the first component to fail because of hightemperatures encountered during periods of high stress of the motor. Thearmature 102 of the present invention, with its integrally molded fan122, is significantly more resistant to failure due to hightemperatures.

[0083] The injection molding of a thermally conductive plastic may alsomore efficiently fill the spaces and voids inbetween the magnet wires110 extending through the lamination stack slots 108, thus promotingeven more efficient cooling of the armature 102 during use.

[0084] In an aspect of the invention, plastic 116 is molded tocompletely encapsulate all the elements of armature 102, includinglamination stack 106 and commutator 114. Thereafter, excess plastic 116is removed from armature 102, such as by machining, to expose thoseportions of armature 102 that need to be exposed, such as the surface ofcommutator 114 and the surface of lamination stack 106.

[0085] Encapsulation also provides enhanced mechanical retention ofmagnet wires 110 and can be used in lieu of the adhesive typically usedto secure the armature lead wires 119. Particularly in high vibrationapplications, the armature lead wires must be supported, that is,affixed in place. Otherwise, rotation of the armature and vibration ofthe device in which the motor having the armature is used, such as apower tool, can cause the armature lead wires to vibrate and eventuallyfatigue and break. Typically, during the trickle resin process describedabove, a high viscosity adhesive is applied around the armature leadwires up to where they attach to the commutator. This adhesive providesthe required support for the armature lead wires.

[0086] Plastic 116 is illustratively molded around armature lead wires119 when plastic 116 is molded around magnet wires 110. Plastic 116provides the necessary support for the armature lead wires 119 toprevent them from vibrating when the armature 102 rotates and thedevice, such as a power tool having a motor using armature 102 vibrates.The armature lead wires 119 can thus be supported by the encapsulationof plastic 116 at little or no additional cost. Moreover, the enhancedmechanical retention provided by encapsulation allows larger gaugemagnet wires 110 to be employed on a given size armature, thusincreasing the amp rating which can be attained with a motor of givendimensions over a comparably sized motor employing trickle resin sealingof the magnet wires. The larger gauge magnet wires 110 provide betterheat transfer and lower heat generation, as well as lower resistance asdiscussed below.

[0087] The thermally conductive plastic 116 is a illustratively basepolymer, such as nylon (nylon 4,6, for example), PPS, PPA, liquidcrystal polymer (LCP), or a blend of these, with an appropriate fillpercentage of a thermally conductive material such as ceramic (abrasiveor lubricious) and, illustratively, an appropriate amount of glass fillfor strength. Aluminum oxide is a common type of abrasive ceramic usedin thermally conductive plastic and boron nitride is a common type oflubricious ceramic. It should be understood that other thermallyconductive materials, metallic or non-metallic, can be used as the fillmaterial, such as aluminum nitride, aluminum or copper. By using a blendfor the base polymer, some of advantages of using a more expensivepolymer, such as LCP, can be realized without incurring the cost ofusing 100% of the more expensive polymer as the base polymer. Forexample, blending LCP with PPS at a ratio of about 10% LCP to 90% PPSincreases moldability and strength compared to pure PPS. Similarly, asmall amount of nylon could be used instead of LCP.

[0088] Thermally conductive plastic 116 can illustratively be Konduit®thermoplastic commercially available from LNP Engineering Plastics ofExton, Pa. (presently a General Electric company). In this regard, thethermally conductive plastic 116 can illustratively be Konduit®PDX-TF-212-11 modified to have about ten percent more ceramic fill.

[0089] In an aspect of the invention, a “phase change additive” is addedto the material used to encapsulate the armature. As used herein, a“phase change additive” is a material that changes phases, such as fromsolid to liquid or liquid to gas, at a temperature that is below thetemperature at which the material used to encapsulate the armature meltsbut above ambient temperatures. Preferably, the phase change material isone that changes phases from solid to liquid. The phase change additivewould increase the capability of the encapsulation material, such asthermally conductive plastic 116, to handle short term heat spikes thatit might not otherwise be able to dissipate quickly enough. When heatspike occurs, the phase change additive changes phase absorbing heat.The phase change additive may illustratively be compounded in smallspheres or particles that are added to the plastic used to encapsulatethe armature. The capacity of the plastic encapsulating the armature towithstand short heat spikes can then be adjusted by adjusting the amountof phase change additive that is added to it. By using the phase changeadditive, plastic having lower thermal conductivity, that may be lessexpensive, can then be used to encapsulate the armature. Use of thephase change additive could also increase the capacity of plastic 116 towithstand the additional heat generated in spikes in more demandingapplications. Phase change additives can include parafins, waxes,hydrated salts and possibly crystalline plastics such as acetal ornylon. An example of a hydrated salt phase change additive is the TH89°C. available from TEAP Energy of Wangar, Perth Western Australia.

[0090] While plastic 116 is illustratively a thermally conductivethermoplastic, other types of materials can be used to encapsulatearmature 102, including thermoset materials, as long as the material iselectrically non-conductive and has sufficient dielectric strengththroughout the operating temperature of armature 102. In this regard,plastic 116 should illustratively have a dielectric strength of at least250 volts/mil. up to a temperature of 300° C. when armature 102 is usedin a power tool. Further, in those aspects of the invention wherethermal conductivity of the encapsulating material is not needed, thenit need not be thermally conductive. In this regard, while theencapsulation process has been described in the context of injectionmolding, it should be understood that other processes could be used,such as transfer molding or compression molding. The process used would,of course, need to be suitable for the material being used toencapsulate the armature. For example, transfer molding and compressionmolding are typically used to mold thermoset materials and injectionmolding used to mold both thermoplastic and thermoset materials.

[0091] With the armature 102, the thermally conductive plastic 116 maycomprise a high temperature nylon or thermoset material which is furthermixed with a suitable non-ferromagnetic material such as ceramic,aluminum or copper, to provide essentially the same density as that ofthe magnet wires 110. Thus, when each of the lamination stack slots 108are completely filled with the plastic 116 and the magnet wires 110, theweight of the material filling each slot 108 is essentially the same.Since the weight of the material filling each slot 108 is essentiallythe same, the need to balance the armature on a balancing machine, afterthe molding step, is eliminated. Eliminating the balancing steprepresents a substantial cost savings because no longer is the use of abalancing machine required, as well as the manual labor of setting eachof the armatures up on the balancing machine. Instead, once thearmatures have cooled after the injection molding process, the armaturescan proceed to the commutator turning operation and then directly to theassembly stage where they are assembled with other components to formmotors. LNP Engineering Plastics, Inc. is a source of specificallyformulated plastics.

[0092] Turning to FIGS. 6 and 7, another aspect of the invention isdescribed. Elements in common with FIG. 5 will be identified with thesame reference numerals. When plastic 116 is molded to encapsulatedarmature 102, features are molded to improve the process of balancingarmature 102. These features illustratively include one or more of extrasacrificial material molded at the periphery of end coils 117 (FIG. 2)formed by the windings of magnet wires 110 or molded pockets that mayreceive balance weights. Utilizing such features in the balancing ofarmature 102 eliminates the machining of non-homogenous material,eliminates the removal of active iron, permits the thickness of theteeth tops of the teeth of lamination stack 106 to be smaller, andlocates the balance planes nearer to the bearing planes allowing truerbalancing with less material removed or added.

[0093] Referring specifically to FIG. 6, armature 102 includes one ormore balancing rings 124 molded of plastic 116 when plastic 116 ismolded to encapsulate armature 102. Illustratively, a balancing ring ismolded adjacent each axial side of lamination stack 106 over end coils117. With specific reference to FIG. 7, during balancing of armature102, material is removed from one or more of the balancing rings 124 atone or more points 126. Balancing rings 124 are located closer to thebearing planes (not shown) of the motor (not shown) using armature 102and are inert, that is, do not include active iron. Consequently,removing material from balancing rings 124 does not affect the magneticcharacteristics of lamination stack 106 and thus does not adverselyaffect the performance of the motor in the way that removing iron fromlamination stack 106 does.

[0094] In a variation, balancing rings 124 have pockets or cavities 128formed therein. During balancing of armature 102, weights 130 areinserted and fixed in one or more pockets 128 (FIG. 8) (only one ofwhich is identified by reference numeral 128) of one or more ofbalancing rings 124 to balance armature 102. Weights 130 are alsolocated nearer the bearing planes and are also inert. In this variation,balancing rings 124 can be made lighter.

[0095] In another aspect of the invention, the mass of plastic 116, thedistribution of the molded plastic 116, or both, can be varied to adjustthe spinning inertia of armature 102. The mass of plastic 116 can bevaried by varying the amount of plastic 116 used, varying its density,or both. The density of plastic 116 can be varied by, for example, theamount of non-ferromagnetic material mixed with plastic 116. Thedistribution of the molded plastic 116 controls the spinning inertia ofarmature 102 by placing more or less plastic 116 around the axis ofarmature shaft 112, such as closer to or further away from the axis ofarmature shaft 112.

[0096] Armatures, as is known, have a natural frequency at which theyresonate, commonly referred to as the resonant frequency. This frequencyis a function of the geometry and stiffness of the armature. In anotheraspect of the invention, the natural or resonant frequency of armature102 can be adjusted by varying the geometry, physical and/or mechanical(physical) properties of plastic 116. Varying the geometry, physicaland/or mechanical (such as its tensile or flexural modulus) propertiesof plastic 116 varies the stiffness of armature 102. For example,increasing the physical (such as density, hardness, or both) of plastic116 provides vibration damping for armature 102. Also, increasing thestiffness of armature 102 increases its critical speed, that is, therotational speed at which armature 102 resonates. The critical speed ofthe armature is often the limiting factor of how fast a motor can spinin that its speed must be kept below the critical speed. By increasingthe critical speed, the maximum speed at which the motor can be run isincreased, which increases the output power that the motor can provide.For example, applicants have found that using an encapsulated armaturein a small angle grinder (a DeWalt DW802 SAG), the critical speed of thearmature was increased about 11.5%, that is, from 39,300 RPM to 43,800RPM.

[0097] Plastic 116 also provides structural reinforcement aroundarmature shaft 112 to reduce and/or control vibration and flexing ofarmature shaft 112. The geometry and mechanical properties of plastic116 can be adjusted to obtain the desired vibration and/or flexreduction/control of armature shaft 112.

[0098] Bondable wire is typically used to adhere wires, such as magnetwires in a field, together without the addition of glue or varnish in asecondary operation, such as the above described trickle resinoperation. Bondable wire has a layer of material thereon that becomessufficiently viscous when hot that it adheres together adjacent wires inthe bundle of wires forming the coil and then hardens to bond the wirestogether. This forms a coil that is mechanically solid and also hasimproved thermal properties due to the reduction of air pockets betweenwires. One type of bondable wire has a layer of heat activated adhesivethereon. A type of this bondable wire having a layer of heat activatedadhesive thereon is available under the trade name BONDEZE from PhelpsDodge of Fort Wayne, Ind.

[0099] With reference to the embodiment described in FIG. 5, when thethermally conductive plastic 116 is molded around magnet wires 110,thermally conductive plastic 116 may not fill all the interstitial voidsbetween the magnet wires 110. In another aspect of the invention, magnetwires 110 can be bondable wires that are then encapsulated in a hotencapsulation material. In an embodiment, the bondable wire is BONDEZEwire. The heat of the hot encapsulation material, such as injectionmolded thermally conductive plastic 116, activates the layer of heatactivated adhesive on magnet wires 110, bonding magnet wires 110together.

[0100]FIG. 10 shows slot 108 having magnet wires 110 encapsulated inthermally conductive plastic 116 where the heat of the thermallyconductive plastic as it was molded around magnet wires 110 activatedheat activated adhesive 111 bonded magnet wires 110 together. This formsa mechanically solid coil inside thermally conductive plastic 116. Thisreduces or prevents movement of the coil and improves thermal transfer,as described above. This aspect of the invention further contributes tothe elimination of the need for the trickle resin process of bonding themagnet wires together. Further, the heat generated during the moldingprocess activates the heat activated adhesive obviating the need toseparately activate the heat activated adhesive 111, such as by bakingin an oven or passing a current through magnet wires 110 to heat them toactivate the heat activated adhesive. For this aspect of the invention,the temperature of the encapsulation material being used just needs toexceed the temperature required to activate the heat activated adhesiveon the magnet wire 110.

[0101] Turning to FIG. 11, another aspect of this invention isdescribed. FIG. 11 shows magnet wires 110 in one of lamination slots 108encapsulated by thermally conductive plastic 116. By setting thepressure at which the plastic 116 is molded around magnet wires 110 at asufficiently high level, magnet wires 110 can be at least partiallydeformed into polygonal shapes from their original round shape. Thisincreases the surface area contact between magnet wires 110 and thusimproves thermal conductivity from the bottom magnet wires 110 throughthe other magnet wires 110 into thermally conductive plastic 116. It isthought that the foregoing is advantageous when the diameter of magnetwires 110 or the fill pattern of magnet wires 110 (such as how closethey are compacted together) prevents each magnet wire 110 from beingcompletely surrounded by thermally conductive plastic 116.

[0102] In another aspect of this invention, the pressure at which theplastic 116 is molded around magnet wires 110 is set at a sufficientlyhigh level to compact the wires together, providing for an increasedfill rate in lamination slots 108. That is, a higher percentage of thevolume of lamination slots 108 is filled with magnet wires. In thisregard, magnet wires 110 may be initially wound in lamination slots 108so that they extend close to or even beyond an outer surface oflamination stack 106. The pressure of the plastic 116 as it is moldedthen compacts the magnet wires 110 together and forces the compactedmagnet wires 110 into slots 108.

[0103] In an aspect of the invention, coil stays 19 (FIG. 4A) are madeof thermally conductive plastic that is melted or wetted during moldingof plastic 116.

[0104] In an aspect of the invention, plastic 116 replaces coil stays 19of prior art armature 10, and holds magnet wires 110 in place when ithardens.

[0105] In an aspect of the invention, coil stays 19 (FIG. 4B) have holes142 therein. During molding of plastic 116, plastic 116 flows throughand bypasses coil stays 19′. Plastic 116 is illustratively a thermallyconductive plastic, as described, and molding it through holes 142 incoil stays 19′ allows more heat to flow toward the surface of thelamination stack, such as lamination stack 106 (FIG. 5).

[0106] With reference to FIGS. 12 and 13, a larger size magnet wire isused to wind magnet wires 110 (FIG. 13) than to wind magnet wires 16(FIG. 12). Slots 14 in FIG. 12 and slots 108 in FIG. 13 are the samesize. In the embodiment of FIG. 13, plastic 116 is molded at pressurearound magnet wires 110 compacting them together in slots 108 allowingslots 108 to accommodate the magnet wires 110 wound with the larger sizemagnet wire. Magnet wires 110 can thus be a larger size magnet wirecompared to magnet wires 16 of FIG. 12. Thus, magnet wires 110 wound inslots 108 of a given size, which dictates in large part the size of thelamination stack 106 having slots 108, can be a larger size magnet wire.This results in the motor having the magnet wires 110 wound with thelarger size magnet wire having increased power compared with the motorhaving the magnet wires 16 wound with the smaller size magnet wire, yethaving the same size lamination stack. Thus, a higher output motorhaving a given physical size is achieved.

[0107] In an alternative aspect of the foregoing, the magnet wires 110are wound in slots 108 and then compacted, such as by the application ofiso-static pressure, before armature 102 is encapsulated. For example,armature 102, after magnet wires 110 have been wound in slots 108 butbefore armature 102 is encapsulated, is placed in a properly shapedcavity of a fluid bladder, shown schematically as fluid bladder 144 inFIG. 14. The pressure of the fluid in fluid bladder 144 is increased,forcing magnet wires 110 deeper into slots 108. Armature 102 is thenencapsulated, as described above, with the plastic 116 encapsulatingarmature 102 holding magnet wires 110 in slots 108 after plastic 116hardens. In a variation of the above, magnet wires 110 are made ofbondable wire, as described above, which are thermally cured during thecompaction of magnet wires 110 by fluid bladder 144.

[0108] With reference to the prior art armature shown in FIG. 3, anotheraspect of the invention is described. In this aspect of the invention,prior art armature 40 is modified by making it using thermallyconductive plastic as the plastic in which armature shaft 44 andlamination stack 42 are insert molded. The thermally conductive plasticforms end spiders 48 and slot liners 50 in the manner described aboveand is also molded between shaft 44 and lamination stack 42 of armature40 to electrically insulate shaft 44 from lamination stack 42. In thisregard, the thermally conductive plastic is selected to have adequatethermal conductivity and dielectric strength or electrically insulativeproperties. The thermally conductive plastic can illustratively beKonduit.®

[0109] In armatures encapsulated in plastic it is important that plasticflash be prevented from entering the slots in the commutator ring whenthe plastic is molded. If flash enters the slots in the commutator ring,it may project outwardly from the slots and create a bump or ridge thatthe brushes will contact when the armature rotates.

[0110] An aspect of the invention described with reference to FIGS.17-18 prevents flash from getting into the slots of a tang typecommutator ring. An armature 300 has a shaft 302 and a lamination stack304. A commutator 306 is mounted on one end of shaft 302. Commutator 306includes a copper commutator ring 308, divided into a plurality ofsegments 310, around a cylindrical core 312, with slots 314 betweenadjacent segments 310. Cylindrical core 312 is made of an electricallyinsulative material, such as phenolic.

[0111] Each commutator segment 310 has a tang 318 extending from anaxial inner end 326. Tangs 318 are electrically connected to ends of themagnet wires (such as magnet wires 110 of FIG. 5) in known fashion.

[0112] To form commutator 306, notches 322 are cut around axial innerend of commutator ring 308. Notches 322 are positioned so that they arebelow the track followed by the brushes (not shown) of the motor inwhich armature 300 is used and to be at the axial inner ends of slots314 when they are cut. Plastic 316 is next molded in commutator ring308, such as by insert molding commutator ring 308, to form cylindricalcore 312 therein. Plastic 316 is illustratively phenolic. Plastic 316fills notches 322.

[0113] Slots 314 are then cut in commutator ring 308. Slots 314 extendradially through commutator ring 308 and run axially from an axial outerend 324 of commutator ring 308 part way into the plastic 316 that fillednotches 322.

[0114] Commutator 306, shaft 302 and lamination stack 304 are nextassembled together and the ends of the magnet wires of armature 300 areconnected to tangs 318 in conventional fashion. Shaft 302, withcommutator 306, and lamination stack 304 are then placed in a mold 400(shown representatively in FIG. 19) and plastic 328 (FIG. 17) moldedaround them to form armature 300 in similar manner to that describedabove with respect to FIG. 5 with the following differences. Mold 400 isprovided with projections 402 that fit between tangs 318 over notches322. Projections 402 prevent plastic 328 from flowing into slots 314from the sides of slots 314 by providing thin wall flow regions thatallow the plastic to freeze off quicker. The plastic 316 that fillednotches 322 when cylindrical core 312 was molded prevents plastic 328from flowing axially into slots 314 from the inner ends 320 of slots314.

[0115] Turning to FIGS. 20 and 21, another aspect of the invention forpreventing flash from getting into the commutator slots in a stuffertype commutator is described. In a stuffer type commutator, inner endsof the segments of the commutator ring have slots into which ends of themagnet wires are pressed.

[0116] An armature 501 has a shaft 503 on which commutator 500, which isa stuffer type commutator, is mounted in known fashion. As is known, astuffer type commutator, such as commutator 500, has a commutator ring516 with slots 504 between segments 514. Inserts 502 extend part wayinto slots 504 from an inner end 506 of commutator ring 516. Inserts 502are illustratively made of mica or plastic. Ends of magnet wires 510 arepressed into slots (not shown) in ends 508 of segments 514 of commutatorring 516.

[0117] Armature 501 is encapsulated by molding plastic 512 around itsshaft 503 and lamination stack 505 in a manner similar to that describedabove. The tool or mold used in molding plastic 512 is configured sothat it seals around inner end 506 of commutator ring 516 where inserts502 are located in slots 504 of commutator ring 516, such at 518.Illustratively, ends 520 of inserts 502 extend distally beyond the point518 where the tool seals around inner end 506 of commutator 500 and arethus disposed underneath the tool. When plastic 512 is molded, plastic512 is molded around inner end 506 of commutator ring 516 only whereinserts 502 are in slots 504 and plastic 512 is thereby prevented fromflowing into slots 504.

[0118] Turning to FIG. 22, another aspect of the invention is described.An armature 600 is encapsulated by molding thermally conductive plastic602 around its shaft 604 and lamination stack 606. The tool or mold usedto mold the plastic 602 is configured so that the slots 608 betweenteeth 610 of lamination stack 606 are cored out. As used herein, coredout means that the plastic 602 is not molded to top surfaces 611 of thelamination teeth 610, so that the plastic molded in the slots 608 isrecessed from the top surfaces of the lamination teeth 610, formingrecesses 612, through which cooling air can flow. By coring out slots608, heat transfer is improved, less plastic is used and recesses 612can be used by tools in subsequent armature manufacturing operations,such as for orienting, locating and/or indexing armature 600. In thisregard, the tool used in molding plastic 602 can have features, such asblades, that fit within slots 608 to form recesses 612 and these bladescan also hold armature 600 in the correct radial position duringmolding. The surface of plastic 602 can be textured to increase thesurface area of the plastic and/or cause turbulence, thus increasingheat transfer, without taking up additional space. The texturing cantake the form of a pattern 613, such as a diamonds, squares, circles,bumps, dimples, and the like. Illustratively, the texturing is done onthe surface of plastic 602 at an end of lamination stack 606 opposite anend of lamination stack 606 where fan 122 is formed.

[0119]FIG. 23 shows a variation of the just discussed aspect of theinvention. The same reference numbers are used to identify likeelements. In FIG. 23, when plastic 602 is molded to encapsulate armature600, integral features are formed, such as fins 614, that increasesurface area and create turbulence. FIGS. 34 and 35 show differentlyshaped fins 614, only two of which are identified by reference numeral614 therein.

[0120]FIG. 24 shows another variation of the just discussed aspect ofthe invention. The same reference numbers are used to identify likeelements. In FIG. 24, plastic 602 is molded so that a necked down region616 is formed between the lamination stack 606 of armature 600 andcommutator 618, which reduces the amount of plastic required. Thesurface of plastic 602 is textured as described above to enhance heattransfer, or features such as fins 614 (FIG. 24) formed thereon.

[0121] In addition to or in lieu of forming the features such asrecesses 612, texture pattern 613, fins 614 and necked down region 616during molding plastic 602, they can be formed in secondary operationssuch as milling, turning or grinding. However, forming these featuresduring molding plastic 602 allows less plastic to be used than if theplastic 602 is removed from armature 600 during a secondary operation toform the feature.

[0122] Turning to FIGS. 25-27, another aspect of the invention isdescribed that provides better thermal conductively than that providedby using thermally conductive plastics, which typically have a thermalconductivity in the 1 to 10 W/m-K. Features 700 are insert molded ontoarmature 102 during the molding of plastic 116 or features 700 aremolded from plastic 116 and then metallized. Features 700 mayillustratively be a finned metal or ceramic end coil cover 700′ that isinsert molded onto armature 102 during the molding of plastic 116.Plastic 116, which is illustratively thermally conductive plastic asdescribed above, is molded to form a thin layer between end coils 117 ofmagnet wires 110 and the finned end coil cover 700.′ With specificreference to FIG. 25, finned end coil cover 700′ also includes a fan 702shown in phantom in FIG. 25 affixed thereto or formed integrallytherewith. In a variation, finned end coil cover 700′ is molded from athermally conductive plastic having a higher thermal conductivity thanplastic 116. With specific reference to FIGS. 25 and 27, features 700,such as fins, posts, or blades which are designated as 700″ in FIG. 27,are molded out plastic 116 when plastic 116 is molded to encapsulatearmature 102. End domes 704 including the features 700″ are then coveredwith a thin metallic layer 706, such as by metallizing them with a vapordeposition or other metallization process.

[0123] In another aspect of the invention, the plastic, such as plastic116 (FIG. 5) molded around lamination stack 106, portions of commutator114 and armature shaft 112 helps hold lamination stack 106 andcommutator 114 on armature shaft 112 and improves twist torque. Twisttorque, as that term is commonly understood, is the amount of torquedifferential between armature shaft 112 and lamination stack 106 orcommutator 114 that can be withstood before armature shaft 112 turnswithin lamination stack 106 or commutator 114. In a variation of thisaspect of the invention, an armature shaft 112 a (FIG. 28) is providedwith features that interlock with the plastic 116 molded around them tofurther improve twist torque. These features can include one or moreflats 710, projections 712, or other features that interlock with theplastic 116 when plastic 116 is molded around them.

[0124] Turning to FIGS. 29 and 30, another aspect of the invention isdescribed where the armature is a double insulated armature. Elements inFIGS. 29 and 30 common to the elements in FIG. 5 are identified with thesame reference numerals.

[0125]FIG. 29 shows a double insulated armature 800 having a protectinginsulating sleeve 802 disposed around shaft 112. Commutator 114 andlamination stack 106 are mounted on shaft 112 with insulating sleeve 802disposed between lamination stack 106 and shaft 112 and betweencommutator 114 and shaft 112. Armature 800 includes magnet wires 110wound in slots 108 of lamination stack 106. Plastic 116 is molded overthe armature 800 so that the plastic 116 flows into and through each ofthe slots 108 and around end coils 117 of magnet wires 110.

[0126] Armature 800 is illustratively formed by first placing insulatingsleeve 802 on shaft 112. It should be understood that insulating sleevecan be made of other materials, such as high-temperature, glassreinforced thermosetting resin. It could also be preformed and thenplaced on shaft 112. Shaft 112 with insulating sleeve 802 thereon isthen in situ molded with lamination stack 106, such as by moldingplastic 116. Plastic 116 is electrically insulative and forms thefunctional insulation layer on the axial ends and in the slots 108 ofarmature 800. In this regard, the mold is made so that plastic 116 ismolded in slots 108 so as to coat the walls of lamination stack 106leaving the remainder of slots 108 open, as well as to form the endspiders around the axial ends of lamination stack 106, such as describedabove with reference to FIG. 3. Magnet wires 110 are then wound in slots108 and ends of magnet wires 110 (FIG. 5) affixed to commutator 114,which has been placed on shaft 112 over insulating sleeve 802. Theresulting assembly is then placed in a suitable molding tool and plastic116 molded around the desired elements of armature 800. Plastic 116 isillustratively a thermally conductive plastic as described above and itis injection molded around the elements of armature 800. Plastic 116 isalso illustratively electrically insulative.

[0127] In double insulated armatures, it is important that theprotective insulation barrier be complete and uninterrupted. If theinsulated sleeve is bridged by the functional insulation, particularlyif the functional insulation is a thermally conductive resin, there isthe possibility of excessive leakage currents during overly abusiveloads as the thermally conductive resin's electrical properties, e.g.,dielectric strength and bulk resistivity, deteriorates at nearlydestructive temperatures.

[0128] An uninterrupted barrier is easy to achieve when the laminationstack, windings and commutator are all separated from the shaft by theinsulative sleeve, such as when the insulative sleeve runs the entirelength of the shaft such as shown with respect to sleeve 802 and shaft112 in FIG. 29. However, design constraints sometimes do not allow asufficient radial distance for the commutator to be placed on theinsulative sleeve and must be placed directly on the shaft without theinsulative sleeve therebetween. In these cases, the commutator must beconstructed so that its insulation barrier provides reinforcedinsulation spacings and properties.

[0129] Turning to FIG. 30, a double insulated armature 810 withcommutator 114 placed directly on shaft 112 without an insulative sleevebetween it and shaft 112 is shown. Insulative sleeve 812 is disposed onshaft 112 between lamination stack 106 and shaft 112 and extends axiallyup to commutator 114. Any gap between the end of insulative sleeve 812and commutator 114 is sealed by high temperature seal 814 and preventsplastic 116, which is illustratively thermally conductive plastic asdiscussed, from flowing into any gap between the end of insulativesleeve 812 and commutator 114 when plastic 116 is molded to encapsulatearmature 810. Instead of seal 814, labyrinths, dams or high temperaturegaskets can be used.

[0130] Turning to FIG. 31, an alternative embodiment of a doubleinsulated, encapsulated armature is shown. Armature 900 has laminationstack 106 and commutator 114 directly mounted on an internal shaft 902and is encapsulated with plastic 116, which is illustratively thermallyconductive plastic as discussed. Internal shaft 902 is coupled to anexternal pinion 904 and bearing journal 906 that has a cylindricalcavity 908 lined with a layer of electrical insulation 910. While FIG.31 shows internal shaft 902 received in insulated cylindrical cavity908, it should be understood that bearing journal 906 could be reversedand external pinion 904 received in insulated cylindrical cavity 908.The foregoing embodiment shown in FIG. 31 provides a double-insulatedarmature where the protecting insulation is distinct and discrete fromthe heat generating portions of the armature.

[0131] Turning to FIGS. 32-35, a three-plate mold 1000 used for moldingplastic 116 to encapsulate armature 102 is shown. Elements in FIGS.32-35 that are common with elements in FIG. 5 will be identified withthe same reference numerals. Three plate mold 1000 is shown in a moldingmachine 1002, which is illustratively a plastic injection moldingmachine, with armature 102 therein. Three plate mold 1000 includes coreplate 1004, cavity plate 1006 and runner plate 1008. Core plate 1004 hasa generally can shaped cavity 1005 in which armature 102 is received,commutator 114 first. That is, armature 102 is received in core plate1004 with commutator 114 adjacent an end or bottom (as oriented in FIG.32) 1010 of core plate 1004. Core plate 1004 may include a pressuretransducer port 1012 in communication with a pressure transducer 1014therein.

[0132] Runner plate 1008 has a hole 1024 therein through which armatureshaft 112 extends when armature 102 is in mold 1000. In runner plate1008, a runner 1017 splits into two semicircular runners 1018 (shown indashed lines in FIG. 33) around hole 1024 in which shaft 112 of armature102 is received when armature 102 is in mold 1000. Semicircular runners1018 form a ring runner 1019. The runner 1017 extends to an exit 1021 ofa hot sprue 1022. Cavity plate 1006 includes drop passages 1016extending from ring runner 1019 in runner plate 1008 to gates 1020.Gates 1020 are preferably located so that they are between slots 108 ofarmature 102 when armature 102 is in mold 1000 and in spaced relation toends 107 of slots 108. With specific reference to FIG. 34, a gate 1020is located between and above adjacent slots 108 of lamination stack 106.Consequently, each gate 1020 feeds two slots 108 of lamination stack106.

[0133] With specific reference to FIG. 36, core plate 1004 may have keys1026 that engage slots 108 in lamination stack 106 of armature 102 tolocate armature 102 in mold 1000 so that gates 1020 are disposed betweenadjacent slots 108 of lamination stack 106. Illustratively, each slot108 has one of keys 1026 projecting into it, which key illustrativelyextends the length of that slot 108. The keys 1026 are preferably sizedto provide thin wall flow regions before the outside diameter oflamination stack 106. This causes plastic 116 to start freezing offbefore it reaches the outside diameter of lamination stack 106,minimizing the chance of flashing to the outside diameter of laminationstack 106. Also, locating gates 1020 between slots 108 may preventplastic 116 from “jetting” down the slots 108 before filling thin wallareas above the coils of magnet wires 110. This is important with mostthermally conductive plastics in that once the melt front stops, thethermally conductive plastic quickly freezes and won't flow again. Thus,if the plastic 116 “jets” down the slots, it may not be possible to packout the thin wall areas afterwards.

[0134] In operation, armature 102 (in its pre-encapsulated state) isplaced in core plate 1004 of mold 1000, commutator 114 first. Cavityplate 1006 is then closed over the other end of armature 102 and runnerplate 1008 closed over cavity plate 1006. Plastic 116 is then injectedinto mold 1000, flowing from hot sprue 1022 through runner 1017 intosemicircular runners 1018 of ring runner 1019, through drop passages1016 in cavity plate 1006, through gates 1020 and around armature 102 inmold 1000. It should be understood that other gate configurations can beused, such as ring and flash gates on three-plate molds and tab gates ontwo-plate molds.

[0135] The pressure in the cavity of mold 1000 is monitored usingpressure transducer 1014. Port 1012 in core plate 1004 is illustrativelypositioned toward bottom 1010 of core plate 1004 so that the pressure inthe cavity of mold 1000 is monitored generally at the opposite ends ofwhere gates 1020 are located. When the pressure in the cavity of mold1000 reaches a predetermined level, as sensed by pressure transducer1014, the injection molding machine is switched from its fill stage toits packing stage. As is known, during the fill stage, the shot pressureis high. Once the mold cavity is nearly filled, the injection moldingmachine is switched to the packing stage where the shot pressure isbacked off to a lower level. The shot pressure is then maintained atthis lower level until the plastic hardens, typically determined bywaiting a set period of time. By using the pressure in the cavity ofmold 1000 to determine when to switch from the fill stage to thepackaging stage, as opposed to constant molding parameter such as shotsize, injection time, etc., effects of variations in the materialproperties of the plastic can be reduced.

[0136] Illustratively, this predetermined pressure is set at a levelthat indicates that the cavity of mold 1000 is nearly filled withplastic 116. A technique known as “scientific molding” is illustrativelyused to control injection molding machine 1002 to minimize the chance offlashing at commutator 114. One such scientific molding technique is theDECOUPLED MOLDING^(SM) technique available from RJG Associates, Inc. ofTraverse City, Mi.

[0137] Pressure transducer 1014 could also be used to determine if apart is molded correctly. That is, a determination is made whether thepressure in the cavity of mold 1000 reached a sufficient level so thatthe cavity of mold 1000 was completely filled. If not, the part isrejected. In this regard a good/bad indicator may be driven based on themonitored pressure in the cavity of mold 1000 to alert the operator ofinjection molding machine 1002 whether the molded part is good or bad.Injection molding machine 1002 may also be configured to automaticallyaccept or reject a part based on the monitored pressure.

[0138] Referring to FIG. 37, a mold 1100, which is illustratively atwo-plate mold, is shown schematically. Two plate mold 1100 is formed tohave overflow tab cavities 1102 to allow overflow tabs 1104 to be formedwhen plastic 116 is molded to encapsulate armature 102. Illustratively,overflow tabs are formed adjacent commutator 114. Overflows tabs 1104help control molding pressure at commutator 114, helping to preventflash while still providing a complete fill and encapsulating of magnetwires 110 with plastic 116. Gates 1106 extend from cavity 1108 of mold1100 to each overflow tab cavity 1102. Gates 1106 are sized so that asmolding pressure builds up in cavity 1108, the plastic 116 flows intothe overflow tab cavities 1102 before flashing over commutator 114.Because most thermally conductive plastics set up quickly, delaying themelt front at the commutator 114 enables the plastic 116 to freeze offin the area of commutator 114 so that when the overflow tab cavities1102 are full and the pressure in cavity 1108 continues to build up, therisk of flash over commutator 114 is minimized or eliminated. Thede-gating process would illustratively accommodate the overflow tabs1104 as additional runners that are removed during the de-gating processso that no additional cycle time results. It should be understood thatoverflow tabs 1104 can be any shape or size sufficient to delay thebuild-up of pressure in mold 1100.

[0139] In another aspect of the invention, features that mayillustratively be molded when the armature, such as armature 102, isencapsulated with plastic, such as plastic 116, but that must bephysically robust, can be pre-formed, such as by pre-molding them out ofa sufficiently strong plastic, and then insert molded when the armatureis encapsulated. This allows the use of a thermally conductive plasticthat does not provide the physical robustness required by these featuresbut has other properties, such as better thermal conductivity, than theplastics that provide the physical robustness required by thesefeatures. With reference to FIG. 5, fan 122 is an example of a featurethat requires a certain degree of physical robustness. Fan 122 can bepre-formed, such as by pre-molding it if a plastic that provides thenecessary physical robustness and then insert molded to attach it toarmature 102 when armature 102 is encapsulated with plastic 116. Plastic116 can then be selected from plastics having the optimumcharacteristics for encapsulating armature 102 even if such plastics donot provide the physical robustness needed by fan 122. This would permita lower cost material to be used for plastic 116 than would be the caseif plastic 116 is also used to mold fan 122 in the manner discussedabove. Use of the higher cost plastic that provides more robust physicalcharacteristics would then be limited to those features that require thegreater degree of physical robustness. This would also permit a plastichaving high thermal conductivity but that is structurally weak or haslittle impact strength to be used for plastic 116 with fan 122 beingpre-formed of the higher strength plastic.

[0140] While foregoing aspects of the invention have been described withreference to an armature of an electric motor, many of the principlesare applicable to other coil structures used in dynamoelectric machines,such as stators for electric motors and coil structures for generatorsand alternators. FIG. 15 shows a stator 150 for an electric motor, suchas motor 100 (FIG. 5). Stator 150 includes a lamination stack 151 havinga plurality of slots 152 therein. Magnet wires 154 are wound in slots152 to form coils 156. Thermally conductive plastic 158 is molded atleast partially around magnet wires 154 and preferably completelyencapsulates magnet wires 154. Similarly, the surface of plastic 158 canbe molded with features, such as fins, or textured to enhance heattransfer, the features metallized, or features pre-formed and insertmolded when plastic is molded around magnet wires 154.

[0141]FIG. 16 illustrates the application of the invention describedwith respect to FIG. 3 to a stator. A stator 250 has a lamination stack252. Lamination stack 252 has a plurality of slots 254 lined with slotliners 260 made of thermally conductive plastic. Magnet wires 256 arewound in slots 254 forming coils 258. Thermally conductive plastic ismolded in slots 254 to form slot liners 260, which electrically insulatemagnet wires 256 from lamination stack 252 as well as enhance heattransfer from magnet wires 256. In this regard, the thermally conductiveplastic is selected to have a desired thermal conductivity anddielectric strength or electrically insulative properties.

[0142] The description of the invention is merely exemplary in natureand, thus, variations that do not depart from the gist of the inventionare intended to be within the scope of the invention. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention.

What is claimed is:
 1. A method of making an armature, comprising:placing a commutator and a lamination stack on a armature shaft, thecommutator having a commutator ring with a plurality of segments withslots between adjacent segments, the commutator ring having notches ataxial inner ends of the slots, the notches filled with an electricallynon-conductive material, each segment having a tang at an axial innerend; attaching ends of coil windings wound in slots in the laminationstack to the tangs of the commutator segments; placing the armatureshaft, commutator and lamination stack in a mold having projections thatextend between the tangs; and molding plastic around at least portionsof the armature shaft, commutator and coil windings, the projections andfilled notches preventing plastic from flowing into the slots betweenthe commutator segments.
 2. The method of claim 1 wherein the slotsextend axially part way into the notches.
 3. The method of claim 1wherein a core of the electrically non-conductive material is molded inthe commutator ring with the non-conductive material filling the notchesduring molding, the core molded to have a cylindrical hole extendingaxially through its center.
 4. The method of claim 3 wherein theelectrically non-conductive material is phenolic.
 5. A method of makingan armature, comprising: placing a stuffer type commutator and alamination stack on a armature shaft, the commutator having a commutatorring with a plurality of segments with slots between adjacent segments,each segment having a wire receiving slot at an axial inner end of thecommutator ring, the commutator ring having inserts of insulativematerial extending axially part way into the slots between the adjacentsegments from the axial inner end of the commutator ring; placing endsof coil windings wound in slots in the lamination stack to wirereceiving slots of the commutator segments; placing the armature shaft,commutator and lamination stack assembly in a mold that has a portionthat fits around the commutator ring over the inserts; and moldingplastic around at least portions of the armature shaft, commutator andlamination stack, the portion of the mold that fits around thecommutator ring over the inserts preventing the plastic from flowinginto the slots between the commutator segments.
 6. A coil structure fora dynamoelectric machine, comprising: a lamination stack having aplurality of slots in which magnet wires are wound forming coils andthermally conductive plastic molded around the magnet wires with atleast a feature formed in the thermally conductive plastic to enhanceheat transfer.
 7. The apparatus of claim 6 wherein the feature includesfins.
 8. The apparatus of claim 6 wherein the feature includes at leasta portion of a surface of the thermally conductive plastic beingtextured.
 9. The apparatus of claim 8 wherein the textured surface ofthe thermally conductive plastic is textured by a pattern formed whenthe thermally conductive plastic is molded.
 10. The apparatus of claim 6wherein the coil structure is a coil structure for an armature of anelectric motor.
 11. The apparatus of claim 6 wherein the coil structureis a coil structure for a stator of an electric motor.
 12. The apparatusof claim 6 wherein the dynamoelectric machine is a generator.
 13. Theapparatus of claim 6 wherein the dynamoelectric machine is analternator.
 14. An armature for an electric motor, comprising: a shafthaving a lamination stack thereon, the lamination stack having aplurality of slots in which magnet wires are wound forming coils,thermally conductive plastic molded at least partially around the magnetwires with at least a feature formed in the thermally conductive plasticto enhance heat transfer.
 15. The apparatus of claim 14 and furtherincluding a fan affixed to at least one of the shaft and the laminationstack, the thermally conductive plastic molded around the shaft of thearmature at ends of the lamination stack, the at least one featureformed in the plastic molded at a end of the lamination stack oppositean end of the lamination stack where the fan is affixed.
 16. Theapparatus of claim 15 wherein the at least one feature includes fins.17. The apparatus of claim 15 wherein the fan is molded from thethermally conductive plastic when the thermally conductive plastic ismolded at least partially around the magnet wires.
 18. The apparatus ofclaim 15 wherein the at least one feature includes at least a portion ofa surface of the thermally conductive plastic being textured.
 19. Theapparatus of claim 18 wherein the texture includes a pattern formed inthe surface of the thermally conductive plastic when the thermallyconductive plastic is molded.
 20. The apparatus of claim 14 wherein thethermally conductive plastic is molded around the magnet wires in theslots in the lamination stack to cover the magnet wires in the slots andso that an outer surface of the plastic is recessed from an outersurface of the lamination stack.
 21. An armature for an electric motor,comprising: a shaft having a lamination stack thereon, the laminationstack having a plurality of slots in which magnet wires are woundforming coils, thermally conductive plastic molded at least partiallyaround the magnet wires to cover the magnet wires in the slots and sothat an outer surface of the plastic is recessed from an outer surfaceof the lamination stack.
 22. The apparatus of claim 21 and furtherincluding at least a feature formed in the thermally conductive plasticto enhance heat transfer.
 23. The apparatus of claim 22 and furtherincluding a fan affixed to at least one of the shaft and the laminationstack, the thermally conductive plastic molded around the shaft of thearmature at ends of the lamination stack, the at least one featureformed in the plastic molded at the end of the lamination stack oppositethe end of the lamination stack where the fan is affixed.
 24. Theapparatus of claim 23 wherein the fan is molded from the thermallyconductive plastic when the thermally conductive plastic is molded atleast partially around the magnet wires.
 25. The apparatus of claim 21wherein the feature includes at least a portion of a surface of thethermally conductive plastic being textured.
 26. The apparatus of claim25 wherein the texture includes a pattern formed in the surface of thethermally conductive plastic when the thermally conductive plastic ismolded.
 27. An armature for an electric motor, comprising: a shafthaving a lamination stack thereon, the lamination stack having aplurality of slots in which magnet wires are wound forming coils,thermally conductive plastic molded around the magnet wires and theshaft to encapsulate the magnet wires, the thermally conductive plasticmolded to form a fan on one end of the shaft extending from an end ofthe lamination stack, the plastic molded around the magnet wires in theslots so that an outer surface of the plastic is recessed from an outersurface of the lamination stack forming recesses between teeth of thelamination stack.
 28. The apparatus of claim 27 wherein at least onefeature is formed in a surface of the thermally conductive plasticmolded at an end of the lamination stack opposite the end of thelamination stack from which the end of the shaft having the fan extends.29. The apparatus of claim 28 wherein the at least one feature includesfins.
 30. The apparatus of claim 29 wherein the at least one featureincludes at least a portion of the surface of the thermally conductiveplastic being textured.
 31. The apparatus of claim 30 wherein thesurface of the thermally conductive plastic is textured with a patternformed in it during the molding of the thermally conductive plastic. 32.A stator for an electric motor, comprising: a lamination stack having aplurality of slots in which magnet wires are wound forming coils,thermally conductive plastic molded at least partially around the magnetwires with at least one feature formed in the thermally conductiveplastic to enhance heat transfer.
 33. The apparatus of claim 32 whereinthe at least one feature includes fins.
 34. The apparatus of claim 32wherein the at least one feature includes at least a portion of asurface of the thermally conductive plastic being textured.
 35. Theapparatus of claim 34 wherein the textured surface of the thermallyconductive plastic is textured with a pattern formed in it duringmolding of the thermally conductive plastic.
 36. A coil structure for adynamoelectric machine, comprising: a lamination stack having aplurality of slots therein lined with slot liners made of thermallyconductive plastic and magnet wires wound in the slots forming coils.37. The apparatus of claim 36 wherein thermally conductive plastic ismolded in the slots of the lamination stack to form the slot liners. 38.The apparatus of claim 37 wherein the coil structure is a coil structurefor an armature of an electric motor.
 39. The apparatus of claim 37wherein the coil structure is a coil structure for a stator of anelectric motor.
 40. The apparatus of claim 37 wherein the dynamoelectricmachine is an alternator.
 41. The apparatus of claim 37 wherein thedynamoelectric machine is a generator.
 42. An armature for an electricmotor, comprising: a shaft having a lamination stack thereon, thelamination stack having a plurality of slots therein lined with slotliners made of thermally conductive plastic, magnet wires wound in theslots in the lamination stack forming coils, and a commutator affixed toone end of the shaft with ends of the magnet wires affixed to thecommutator.
 43. The apparatus of claim 42 wherein the thermallyconductive plastic is molded in the slots in the lamination stack toform the slot liners.
 44. The apparatus of claim 43 wherein thethermally conductive plastic is molded around the armature shaft at endsof the lamination stack to form end spiders.
 45. A method of making anarmature for an electric motor, comprising: placing a lamination stackhaving a plurality of slots therein on a shaft; lining the slots withslot liners made of thermally conductive plastic; affixing a commutatorto an end of the shaft; winding magnet wires in the slots to form coils;and affixing ends of the magnet wires to the commutator.
 46. The methodof claim 45 wherein the thermally conductive plastic is molded in theslots in the lamination stack to form the slot liners.
 47. The method ofclaim 45 wherein the thermally conductive plastic is molded around theshaft at ends of the lamination stack to form end spiders.
 48. A statorfor an electric motor, comprising: a lamination stack having a pluralityof slots therein lined with slot liners made of thermally conductiveplastic and magnet wires wound in the slots forming coils.
 49. Theapparatus of claim 48 wherein the thermally conductive plastic is moldedin the slots of the lamination stack to form the slot liners.
 50. Amethod of making a stator for an electric motor comprising lining slotsin a lamination stack with slot liners made of thermally conductiveplastic and winding wire in the slots to form coils.
 51. The method ofclaim 50 wherein thermally conductive plastic is molded in the slots ofthe lamination stack to form the slot liners.
 52. An electric motor,comprising an armature and a stator, the armature having a laminationstack having a plurality of slots therein lined with slot liners made ofthermally conductive plastic and wires wound in the slots forming coils.53. The apparatus of claim 52 wherein the stator has a lamination stackhaving a plurality of slots therein lined with slot liners made ofthermally conductive plastic and wires wound in the slots of thelamination stack of the stator forming coils.
 54. The apparatus of claim52 wherein thermally conductive plastic is molded in the slots of thelamination stack of the armature to form the slot liners lining theslots in the lamination stack of the armature.
 55. The apparatus ofclaim 53 wherein thermally conductive plastic is molded in the slots ofthe lamination stack of the armature and in the slots of the laminationstack of the stator to form the slot liners lining the slots in thelamination stack of the armature and to form the slot liners lining theslots in the lamination stack of the stator.
 56. An electric motor,comprising an armature and a stator, the stator having a laminationstack having a plurality of slots therein lined with slot liners made ofthermally conductive plastic and wires wound in the slots of thelamination stack forming coils.
 57. The apparatus of claim 56 whereinthermally conductive plastic is molded in the slots of the laminationstack to form the slot liners.
 58. An armature for an electric motor,comprising: a shaft having a lamination stack thereon, the laminationstack having a plurality of slots in which magnet wires are woundforming coils, the magnet wires having a layer of heat activatedadhesive thereon, and plastic molded around the magnet wires, the heatof the plastic as it is molded activating the heat activated adhesive onthe magnet wires.
 59. The apparatus of claim 58 wherein the plasticincludes thermally conductive plastic.
 60. The apparatus of claim 58wherein the heat activated adhesive, upon activation, bonds the magnetwires of each coil together to form mechanically solid coils within theplastic.
 61. The apparatus of claim 58 wherein the plastic is moldedaround the magnet wires at a pressure sufficient to at least partiallydeform individual magnet wires into at least partial polygonal shapes.62. An armature for an electric motor, comprising: a shaft having alamination stack thereon, the lamination stack having a plurality ofslots in which magnet wires are wound forming coils, the magnet wireshaving a layer of heat activated adhesive thereon, and thermallyconductive plastic molded around the magnet wires, the heat of theplastic as it is molded activating the heat activated adhesive on themagnet wires to bond the coils of magnet wires into mechanically solidcoils within the plastic to reduce movement of the coils and improvethermal transfer of heat out of the magnet wires.
 63. An electric motor,comprising: a stator; an armature received in the stator, the armaturehaving a shaft and a lamination stack on the shaft, the lamination stackhaving a plurality of slots; magnet wires wound in coils in slots of thelamination stack, the magnet wires having a coating of heat activatedadhesive; and plastic molded around the magnet wires with heat of theplastic activating the heat activated adhesive on the magnet wiresduring molding of the plastic to bond the magnet wires together.
 64. Theapparatus of claim 63 wherein the plastic includes thermally conductiveplastic.
 65. The apparatus of claim 64 wherein the heat activatedadhesive, upon activation, bonds the coils of magnet wires intomechanically solid coils to reduce movement of the coils and to improveheat transfer out of the magnet wires.
 66. The apparatus of claim 63wherein the plastic is molded around the magnet wires at a pressuresufficient to deform individual magnet wires into polygonal shapes. 67.A method of forming an armature for an electric motor, comprising:winding magnet wires having a coating of heat activated adhesive thereonin a plurality of slots in a lamination stack on a shaft to form coils;and molding hot plastic around the magnet wires, the heat of the plasticas it is being molded activating the heat activated adhesive on themagnet wires to bond the magnet wires of each coil together.
 68. Themethod of claim 67 wherein molding hot plastic around the magnet wiresincludes molding hot thermally conductive plastic around the magnetwires.
 69. The method of claim 68 wherein molding hot plastic around themagnet wires activates the heat activated adhesive on the magnet wiresto bond the magnet wires of each coil into a mechanically solid coilwithin the plastic to prevent movement of the coil and enhance heattransfer out of the magnet wires.
 70. The method of claim 67 whereinmolding hot plastic around the magnet wires includes molding the plasticat a pressure sufficient to at least partially deform individual magnetwires into at least partial polygonal shapes.
 71. A stator for anelectric motor, comprising a lamination stack having a plurality ofslots in which magnet wires are wound forming coils, the magnet wireshaving a layer of heat activated adhesive thereon, and plastic moldedaround the magnet wires, the heat of the plastic as it is moldedactivating the heat activated adhesive on the magnet wires.
 72. Theapparatus of claim 71 wherein the plastic includes thermally conductiveplastic.
 73. The apparatus of claim 71 wherein the heat activatedadhesive, upon activation, bonds the magnet wires of each coil togetherto form mechanically solid coils within the plastic.
 74. The apparatusof claim 71 wherein the plastic is molded around the magnet wires at apressure sufficient to at least partially deform individual magnet wiresinto at least partial polygonal shapes.
 75. A stator for an electricmotor, comprising: a lamination stack having a plurality of slots inwhich magnet wires are wound forming coils, the magnet wires having alayer of heat activated adhesive thereon, and thermally conductiveplastic molded around the magnet wires, the heat of the plastic as it ismolded activating the heat activated adhesive on the magnet wires tobond the coils of magnet wires into mechanically solid coils within theplastic to reduce movement of the coils and improve thermal transfer ofheat out of the magnet wires.
 76. An electric motor, comprising: anarmature; a stator, the stator including a lamination stack having aplurality of slots; magnet wires wound in coils in slots of thelamination stack of the stator, the magnet wires having a coating ofheat activated adhesive; and plastic molded around the magnet wires withheat of the plastic activating the heat activated adhesive on the magnetwires during molding of the plastic to bond the magnet wires together.77. The apparatus of claim 76 wherein the plastic includes thermallyconductive plastic.
 78. The apparatus of claim 77 wherein the heatactivated adhesive, upon activation, bonds the coils of the magnet wiresinto mechanically solid coils to reduce movement of the coils and toimprove heat transfer out of the magnet wires.
 79. The apparatus ofclaim 76 wherein the plastic is molded around the magnet wires at apressure sufficient to at least partially deform individual magnet wiresinto at least partial polygonal shapes.
 80. A method of forming a statorfor an electric motor comprising: winding magnet wires having a coatingof heat activated adhesive thereon in a plurality of slots in alamination stack to form coils; and molding hot plastic around themagnet wires, the heat of the plastic as it is being molded activatingthe heat activated adhesive on the magnet wires to bond the magnet wiresof each coil together.
 81. The method of claim 80 wherein molding hotplastic around the magnet wires includes molding hot thermallyconductive plastic around the magnet wires.
 82. The method of claim 81wherein molding hot plastic around the magnet wires activates the heatactivated adhesive on the magnet wires to bond the magnet wires of eachcoil into a mechanically solid coil within the plastic to preventmovement of the coil and enhance heat transfer out of the magnet wires.83. The method of claim 80 wherein molding hot plastic around the magnetwires including molding the plastic at a pressure sufficient to at leastpartially deform individual magnet wires into at least partial polygonalshapes.
 84. A coil structure for a dynamoelectric machine, comprising: alamination stack having a plurality of slots in which magnet wires arewound forming coils, the magnet wires having a layer of heat activatedadhesive thereon, and plastic molded around the magnet wires, the heatof the plastic as it is molded activating the heat activated adhesive onthe magnet wires.
 85. The apparatus of claim 84 wherein thedynamoelectric machine is an electric motor.
 86. The apparatus of claim84 wherein the dynamoelectric machine is an alternator.
 87. Theapparatus of claim 84 wherein the dynamoelectric machine is a generator.88. The apparatus of claim 84 wherein the plastic includes thermallyconductive plastic.
 89. The apparatus of claim 84 wherein the heatactivated adhesive, upon activation, bonds the magnet wires of each coiltogether to form mechanically solid coils within the plastic.
 90. Theapparatus of claim 84 wherein the plastic is molded around the magnetwires at a pressure sufficient to at least partially deform individualmagnet wires into at least partial polygonal shapes.
 91. A method offorming a coil structure for a dynamoelectric machine, comprising:winding magnet wires having a coating of heat activated adhesive thereonin a plurality of slots in a lamination stack on a shaft to form coils;and molding hot plastic around the magnet wires, the heat of the hotplastic activating the heat activated adhesive on the magnet wires tobond the magnet wires of each coil together.
 92. The method of claim 91wherein molding hot plastic around the magnet wires includes molding hotthermally conductive plastic around the magnet wires.
 93. The method ofclaim 92 wherein molding hot plastic around the magnet wires activatesthe heat activated adhesive on the magnet wires to bond the magnet wiresof each coil into a mechanically solid coil within the plastic to reducemovement of the coil and enhance heat transfer out of the magnet wires.94. The method of claim 91 wherein molding hot plastic around the magnetwires includes molding the plastic at a pressure sufficient to at leastpartially deform individual magnet wires into at least partial polygonalshapes.
 95. The method of claim 91 wherein the dynamoelectric machine isan electric motor.
 96. The method of claim 91 wherein the dynamoelectricmachine is an alternator.
 97. The method of claim 91 wherein thedynamoelectric machine is a generator.
 98. A coil structure for adynamoelectric machine, comprising: a lamination stack having aplurality of slots in which magnet wires are wound forming coils andthermally conductive plastic molded around the magnet wires at apressure sufficient to at least partially deform individual magnet wiresinto at least partial polygonal shapes.
 99. The apparatus of claim 98wherein the at least partial deformation of individual magnet wires intoat least partial polygonal shapes increases surface area contact betweenindividual magnet wires to enhance heat transfer from the magnet wiresto the thermally conductive plastic.
 100. The apparatus of claim 99wherein the dynamoelectric machine is an electric motor.
 101. Theapparatus of claim 100 wherein the coil structure is a coil structurefor an armature.
 102. The apparatus of claim 100 wherein the coilstructure is a coil structure for a stator.
 103. The apparatus of claim99 wherein the dynamoelectric machine is an alternator.
 104. Theapparatus of claim 99 wherein the dynamoelectric machine is a generator.105. A method of making a coil structure for a dynamoelectric machine,comprising: winding magnet wires in a plurality of slots in a laminationstack to form coils; molding plastic around the magnet wires at apressure sufficient to at least partially deform individual magnet wiresinto at least partial polygonal shapes.
 106. The method of claim 105wherein the at least partial deformation of individual magnet wires intoat least partial polygonal shapes increases surface area contact betweenindividual magnet wires to enhance heat transfer from the magnet wiresto the thermally conductive plastic.
 107. The method of claim 106wherein the dynamoelectric machine is an electric motor.
 108. The methodof claim 107 wherein the coil structure is an armature.
 109. The methodof claim 107 wherein the coil structure is a stator.
 110. The method ofclaim 106 wherein the dynamoelectric machine is an alternator.
 111. Themethod of claim 106 wherein the dynamoelectric machine is a generator.112. An armature for an electric motor, comprising: a lamination stackhaving slots therein; an armature shaft extending coaxially through thelamination stack; a plurality of magnet wires wound in the slots of thelamination stack; a commutator disposed on the armature shaft to whichends of the magnet wires are electrically coupled; an insulative sleevedisposed on the armature shaft between the lamination stack and thearmature shaft and between the commutator and the armature shaft; andthermally conductive plastic at least partially encasing the magnetwires.
 113. The armature of claim 112 wherein the slots of thelamination stack includes slot liners made of electrically insulativeplastic.
 114. The armature of claim 113 wherein the electricallyinsulative plastic is molded in the slots in the lamination stack toform the slot liners and around the armature shaft at ends of thelamination stack to form end spiders.
 115. The armature of claim 114wherein the electrically insulative plastic is also thermally conductiveplastic.
 116. An armature for an electric motor, comprising: alamination stack having slots therein with slot liners formed ofthermally conductive and electrically insulative plastic, the laminationstack having end spiders formed of the thermally conductive andelectrically insulative plastic; an armature shaft extending coaxiallythrough the lamination stack; a plurality of magnet wires wound in theslots of the lamination stack; a commutator disposed on the armatureshaft to which ends of the magnet wires are electrically coupled; aninsulative sleeve disposed on the armature shaft between the laminationstack and the armature shaft and between the commutator and the armatureshaft; and thermally conductive plastic at least partially encasing themagnet wires.
 117. A method for forming an armature for an electricmotor, comprising: placing an electrically insulative sleeve on anarmature shaft; next securing a lamination stack having slots therein onthe armature shaft with the insulative sleeve disposed therebetween;next molding electrically insulative plastic in the slots of thelamination stack to form slot liners and around the ends of thelamination stack to form end spiders; next securing a commutator on oneend of the armature shaft with the insulative sleeve disposedtherebetween; next winding magnet wires in the slots in the laminationstack and securing ends of the magnet wires to the commutator; and nextmolding thermally conductive plastic to at least partially encase themagnet wires in plastic.
 118. The method of claim 117 wherein placingthe insulative sleeve on the shaft includes applying a ceramic coatingto the shaft.
 119. The method of claim 117 wherein the electricallyinsulative plastic is also thermally conductive plastic.
 120. Anarmature for an electric motor, comprising: a lamination stack havingslots therein; an armature shaft extending coaxially through thelamination stack; a plurality of magnet wires wound in the slots of thelamination stack; a commutator disposed on the armature shaft to whichends of the magnet wires are electrically coupled; an insulative sleevedisposed on the armature shaft between the lamination stack and thearmature shaft and extending to the commutator; an electricallyinsulative seal disposed around the insulative sleeve and abutting thecommutator to seal any gap between an end of the insulative sleeve andthe commutator; and thermally conductive plastic at least partiallyencasing the magnet wires.
 121. The armature of claim 120 wherein theslots of the lamination stack includes slot liners made of electricallyinsulative plastic.
 122. The armature of claim 121 wherein theelectrically insulative plastic is molded in the slots in the laminationstack to form the slot liners and around the armature shaft at ends ofthe lamination stack to form end spiders.
 123. The armature of claim 122wherein the electrically insulative plastic is also thermally conductiveplastic.
 124. An armature for an electric motor, comprising: alamination stack having slots therein with slot liners formed ofthermally conductive and electrically insulative plastic, the laminationstack having end spiders formed of the thermally conductive andelectrically insulative plastic; an armature shaft extending coaxiallythrough the lamination stack; a plurality of magnet wires wound in theslots of the lamination stack; a commutator disposed on the armatureshaft to which ends of the magnet wires are electrically coupled; aninsulative sleeve disposed on the armature shaft between the laminationstack and the armature shaft and extending to the commutator; anelectrically insulative seal disposed around the insulative sleeve andabutting the commutator to seal any gap between an end of the insulativesleeve and the commutator; and thermally conductive plastic at leastpartially encasing the magnet wires.
 125. A method for forming anarmature for an electric motor, comprising: placing an electricallyinsulative sleeve on armature shaft; next securing a lamination stackhaving slots therein on the armature shaft with the insulative sleevedisposed therebetween; next molding electrically insulative plastic inthe slots of the lamination stack to form slot liners and around theends of the lamination stack to form end spiders; next securing acommutator on one end of the armature shaft adjacent an end of theinsulative sleeve; next winding magnet wires in the slots in thelamination stack and securing ends of the magnet wires to thecommutator; and next molding thermally conductive plastic to at leastpartially encase the magnet wires and preventing any of the thermallyconductive plastic from flowing into any gap between the commutator andthe insulative sleeve.
 126. The method of claim 125 wherein preventingany of the thermally conductive plastic from flowing into any gapbetween the commutator and the insulative sleeve includes placing aninsulative seal around the insulative sleeve and abutting the commutatorprior to molding the thermally conductive plastic.
 127. The method ofclaim 125 wherein preventing any of the thermally conductive plasticfrom flowing into any gap between the commutator and the insulativesleeve includes providing a mold used to mold the thermally conductiveplastic with a dam that surrounds the insulative sleeve adjacent thecommutator and abuts the commutator.
 128. The method of claim 125wherein placing the insulative sleeve on the shaft includes applying aceramic coating to the shaft.
 129. The method of claim 125 wherein theelectrically insulative plastic is also thermally conductive plastic.130. A method of manufacturing an armature for an electric motor,comprising: placing a commutator and a lamination stack on an armatureshaft; winding magnet wire in slots in the lamination stacks to formcoils; attaching ends of the magnet wire to the commutator; moldingplastic around the magnet wire and around the shaft of the armature atends of the lamination stack; adjusting a spinning inertia of thearmature by adjusting at least one of a mass of the plastic molded and adistribution of the plastic molded.
 131. The method of claim 130 whereinthe mass of plastic molded is adjusted by varying at least one of thedensity of the plastic molded and the amount of plastic molded.
 132. Themethod of claim 130 wherein adjusting the distribution of the plasticmolded includes adjusting the mass of plastic placed at varyingdistances from an axis of rotation of the armature shaft.
 133. Themethod of claim 130 wherein the plastic is thermally conductive plastic.134. A method of manufacturing an armature for an electric motor,comprising: placing a commutator and a lamination stack on an armatureshaft; winding magnet wire in slots in the lamination stacks to formcoils; attaching ends of the magnet wire to the commutator; moldingplastic around the magnet wire and around the shaft of the armature atends of the lamination stack; adjusting at least one of a resonantfrequency and critical speed of the armature by adjusting at least oneof a geometry of the plastic molded, the physical properties of theplastic and the mechanical properties of the plastic.
 135. The method ofclaim 134 wherein adjusting the geometry of the plastic includes moldinga sufficient amount of the plastic around the armature shaft to reducevibration and flexing of the armature shaft.
 136. The method of claim134 wherein adjusting the mechanical properties of the plastic includesadjusting at least one of its tensile modulus and flexural modulus andadjusting the physical properties of the plastic includes adjusting atleast one of its density and hardness.
 137. The method of claim 134wherein molding the plastic increases vibration damping of the armatureshaft.
 138. The method of claim 134 wherein the plastic is thermallyconductive plastic.
 139. A method of manufacturing an armature for anelectric motor, comprising: placing a commutator and a lamination stackon an armature shaft; winding magnet wire in slots in the laminationstacks to form coils; attaching ends of the magnet wire to thecommutator; and molding plastic around the magnet wire and around theshaft of the armature to stiffen the armature and thereby increase thecritical speed of the armature.
 140. The method of claim 139 wherein theplastic is thermally conductive plastic.
 141. A method for forming agiven size armature to increase the power of an electric motor usingthat armature, comprising: securing a lamination stack having slotstherein on an armature shaft; securing a commutator on one end of thearmature shaft; winding magnet wires in the slots in the laminationstack and securing ends of the magnet wires to the commutator; andmolding plastic to at least partially encase the magnet wires in theplastic; the magnet wires being larger than smaller magnet wires used inan armature of the given size where the magnet wires are not at leastpartially encased in plastic, the electric motor using the given sizearmature having the larger magnet wires having increased power comparedto the electric motor using the given size armature having the smallermagnet wires.
 142. The method of claim 141 wherein the magnet wiresinclude armature lead wires that extend from the slots to the commutatorand molding the plastic includes molding the plastic around the armaturelead wires to support them and prevent them from vibrating when thearmature rotates during operation.
 143. The method of claim 141 whereinthe plastic is molded around the magnet wires in the slots to retainthem in the slots, the larger magnet wires wound in the slots filling alarger volume of the slot than the smaller magnet wires.
 144. The methodof claim 143 wherein the magnet wires include armature lead wires thatextend from the slots to the commutator and molding the plastic includesmolding the plastic around the armature lead wires to support them andprevent them from vibrating when the armature rotates during operation.145. The method of claim 141 and further including applying pressure tothe magnet wires to compress them in the slots.
 146. The method of claim145 wherein applying pressure to the magnet wires includes applying thepressure with the plastic while it is being molded and further includingretaining the magnet wires in the slots with molded plastic.
 147. Themethod of claim 145 wherein applying pressure to the magnet wiresincludes applying the pressure by applying iso-static pressure to themagnet wires before the plastic is molded.
 148. The method of claim 147wherein applying iso-static pressure includes placing the armature withthe magnet wires wound in the slots in the lamination stack in a cavityof a fluid bladder and pressurizing the fluid bladder.
 149. The methodof claim 145 wherein winding magnet wires in the slots includes windingmagnet wires having a layer of heat activated adhesive thereon andactivating the heat activated adhesive with heat of the plastic duringthe molding of the plastic.
 150. The method of claim 141 wherein themagnet wires include armature lead wires that extend from the slots tothe commutator and molding the plastic includes injection molding theplastic around the magnet wires in the slots of the lamination stack,around the armature lead wires and around the ends of the magnet wireswhere they are secured to the commutator.
 151. The method of claim 150wherein winding magnet wires in the slots includes winding magnet wireshaving a layer of heat activated adhesive thereon and activating theheat activated adhesive with heat of the plastic during the molding ofthe plastic.
 152. The method of claim 151 and further including applyingpressure to the magnet wires to compress them in the slots.
 153. Themethod of claim 152 wherein applying pressure to the magnet wiresincludes applying the pressure with the plastic while it is being moldedand retaining the magnet wires in the slots with molded plastic. 154.The method of claim 152 wherein applying pressure to the magnet wiresincludes applying iso-static pressure to the magnet wires before theplastic is molded.
 155. The method of claim 154 wherein applyingiso-static pressure includes placing the armature with the magnet wireswound in the slots in the lamination stack in a cavity of a fluidbladder and pressurizing the fluid bladder.
 156. The method of claim 141wherein the plastic is a thermally conductive plastic.
 157. The methodof claim 156 wherein the plastic has a base polymer and a thermallyconductive additive of at least one of aluminum oxide, boron nitride,and aluminum nitride.
 158. A method for forming a given size armature toincrease the power of an electric motor using that armature, comprising:securing a lamination stack having slots therein on an armature shaft;securing a commutator on one end of the armature shaft; winding magnetwires in the slots in the lamination stack and securing ends of themagnet wires to the commutator; molding plastic over the magnet wires toat least partially encase the magnet wires in the plastic; and retaininga larger volume of magnet wires in the slots with the plastic than in anarmature of the given size where the magnet wires are not at leastpartially encased in plastic, the electric motor using the given sizearmature having the larger volume of magnet wires having increased powercompared to the electric motor using the given size armature having thesmaller volume of magnet wires.
 159. The method of claim 158 wherein thelarger volume of magnet wires includes the same number of turns oflarger magnet wires than smaller magnet wires used in the given sizearmature without the magnet wires at least partially encased in theplastic.
 160. The method of claim 159 wherein the magnet wires includearmature lead wires that extend from the slots to the commutator andmolding the plastic includes molding the plastic over the armature leadwires to support them and prevent them from vibrating when the armaturerotates during operation.
 161. The method of claim 160 and furtherincluding applying pressure to the magnet wires with the plastic whileit is being molded to compress the magnet wires in the slots andretaining the magnet wires in the slots with molded plastic.
 162. Themethod of claim 161 wherein winding magnet wires in the slots includeswinding magnet wires having a layer of heat activated adhesive thereonand activating the heat activated adhesive with heat of the plasticduring the molding of the plastic.
 163. The method of claim 162 whereinthe plastic is a thermally conductive plastic.
 164. The method of claim163 wherein the plastic has a base polymer and a thermally conductiveadditive of at least one of aluminum oxide, boron nitride, and aluminumnitride.
 165. The method of claim 150 and further including applyingiso-static pressure to the magnet wires to compress the magnet wires inthe slots before plastic is molded by placing the armature with themagnet wires wound in the slots in a cavity of a fluid bladder andpressurizing the fluid bladder.
 166. The method of 165 wherein windingmagnet wires in the slots includes winding magnet wires having a layerof heat activated adhesive thereon and activating the heat activatedadhesive with heat of the plastic during the molding of the plastic.167. The method of claim 158 wherein the larger volume of magnet wiresinclude a greater number of turns of magnet wires than in the armatureof the given size without the magnet wires at least partially encased inplastic.
 168. The method of claim 167 wherein the magnet wires includearmature lead wires that extend from the slots to the commutator andmolding the plastic includes molding the plastic over the armature leadwires to support them and prevent them vibrating when the armaturerotates during operation.
 169. The method of claim 168 and furtherincluding applying pressure to the magnet wires with the plastic whileit is being molded to compress the magnet wires in the slots andretaining the magnet wires in the slots with molded plastic.
 170. Themethod of claim 169 wherein winding magnet wires in the slots includeswinding magnet wires having a layer of heat activated adhesive thereonand activating the heat activated adhesive with heat of the plasticduring the molding of the plastic.
 171. The method of claim 170 whereinthe plastic is a thermally conductive plastic.
 172. The method of claim171 wherein the plastic has a base polymer and a thermally conductiveadditive of at least one of aluminum oxide, boron nitride and aluminumnitride.
 173. The method of claim 168 and further including applyingiso-static pressure to the magnet wires to compress the magnet wires inthe slots before plastic is molded by placing the armature with themagnet wires wound in the slots in a cavity of a fluid bladder andpressurizing the fluid bladder.
 174. The method of 173 wherein windingmagnet wires in the slots includes winding magnet wires having a layerof heat activated adhesive thereon and activating the heat activatedadhesive with heat of the plastic during the molding of the plastic.175. A method for forming an armature for an electric motor, comprising:securing a lamination stack having slots therein on an armature shaft;securing a commutator on one end of the armature shaft; winding magnetwires in the slots in the lamination stack and securing ends of themagnet wires to the commutator, the magnet wires having armature leadwires that extend from the slots to the commutator; and molding plasticover the magnet wires to encase at least the armature lead wires inplastic.
 176. The method of claim 175 wherein molding the plasticincludes molding it over the magnet wires in the slots and over the endsof the magnet wires where they are secured to the commutator.
 177. Themethod of claim 176 wherein the plastic is thermally conductive plastic.178. The method of claim 177 wherein the plastic has a base polymer anda thermally conductive additive of at least one of aluminum oxide, boronnitride and aluminum nitride.
 179. A method for forming an armature foran electric motor, comprising: securing a lamination stack having slotstherein on an armature shaft; securing a commutator on one end of thearmature shaft; winding magnet wires in the slots in the laminationstack and securing ends of the magnet wires to the commutator, themagnet wires having armature lead wires that extend from the slots tothe commutator; and molding plastic over the magnet wires to retain themin the slots and to support the armature lead wires and prevent themfrom vibrating when the armature rotates during operation.
 180. Themethod of claim 179 wherein molding the plastic includes molding it overthe magnet wires in the slots and over the ends of the magnet wireswhere they are secured to the commutator.
 181. The method of claim 180wherein the plastic is thermally conductive having a base polymer and athermally conductive additive of at least one of aluminum oxide, boronnitride, and aluminum nitride.
 182. The method of claim 141 wherein theplastic is a thermoplastic and molding the plastic includes injectionmolding it.
 183. The method of claim 141 wherein the plastic is athermoset and molding the plastic includes one of injection molding,transfer molding and compression molding.
 184. The method of claim 158wherein the plastic is a thermoplastic and molding the plastic includesinjection molding it.
 185. The method of claim 159 wherein the plasticis a thermoset and molding the plastic includes one of injectionmolding, transfer molding and compression molding.
 186. The method ofclaim 175 wherein the plastic is a thermoplastic and molding the plasticincludes injection molding it.
 187. The method of claim 175 wherein theplastic is a thermoset and molding the plastic includes one of injectionmolding, transfer molding and compression molding.
 188. A three platemold for use in molding plastic around an armature for an electricmotor, the armature having a shaft with a lamination stack and anarmature affixed to the shaft, the mold comprising: a core plate; acavity plate that closes against the core plate, the cavity plate havinga plurality of passages therein with a gate at each end of each passagethat opens to a cavity of the mold; a runner plate that closes againstthe cavity plate, the runner plate having a shaft opening through whichthe armature shaft extends when the runner plate is closed against thecavity plate and an armature is in the mold cavity, the runner platehaving a ring runner around the shaft opening, the ring runner havingopenings that open to the passages in the cavity plate when the runnerplate is closed against the cavity plate.
 189. The mold of claim 188 andfurther including at least one feature that locates the armature in themold cavity, each gate when the plates are closed located in spacedrelation to an end of the lamination stack and between ends of adjacentslots in the lamination stack so that when plastic flows out of thegates into the mold cavity, it enters the mold cavity in spaced relationto and between ends of adjacent slots in the lamination stack.
 190. Themold of claim 189 wherein the cavity plate has a gate for each two slotsin the lamination stack with each gate feeding two slots of thelamination stack with plastic.
 191. The mold of claim 189 wherein the atleast one feature that locates the armature in the mold includes atleast one key that projects into one of the slots in the laminationstack.
 192. The mold of claim 189 wherein the at least one feature thatlocates the armature in the mold includes a key for each slot thatprojects into that slot and extends the length of the slot that itprojects into, each key sized to provide thin wall flow regions beforean outside diameter of the lamination stack to cause the plastic tostart freezing off before it reaches the outside diameter of thelamination stack.
 193. The mold of claim 188 wherein the ring runnerincludes two semi-circular runners that extend around the shaft openingin the top plate on opposite sides thereof.
 194. The mold of claim 188wherein the core plate includes a pressure transducer port opening intothe cavity of the mold in proximity to the commutator of the armaturewhen the armature is received in the mold cavity.
 195. In a two-platemold for use in molding plastic around an armature for an electricmotor, the improvement comprising the mold having at least one overflowtab cavity.
 196. The mold of claim 195 having a mold cavity with theoverflow tab cavity coupled to the mold cavity by a gate that opensproximate to the commutator of the armature when the armature isreceived in the mold cavity.
 197. The mold of claim 196 wherein the gatecoupling the overflow tab cavity to the mold cavity is sized so that asmolding pressure builds up in the mold cavity, the plastic flows intothe overflow tab cavity before flashing over the commutator of thearmature.
 198. The mold of claim 197 wherein the overflow tab cavityincludes a plurality of overflow tab cavities, each overflow tab cavitycoupled to the mold cavity by a gate that opens proximate to thecommutator of the armature.
 199. The mold of claim 198 wherein theoverflow tab cavities are sized so that when they are full and moldingpressure continues to build up in the mold cavity, the plastic has begunto freeze off in the area of the commutator.
 200. A three plate mold foruse in molding plastic around an armature for an electric motor, thearmature having a shaft with a lamination stack and an armature affixedto the shaft, the mold comprising: a core plate; a cavity plate thatcloses against the core plate, the cavity plate having a gate for everytwo slots in the lamination stack, each gate opening to the mold cavityin spaced relation to an end of the lamination stack and between ends ofadjacent slots in the lamination stack so that each gate feeds plasticto two adjacent slots in the lamination stack, the cavity plate furtherincluding a drop passage for each gate; a runner plate that closesagainst the cavity plate, the runner plate having a shaft openingthrough which the armature shaft extends when the runner plate is closedagainst the cavity plate and an armature is in the mold cavity, therunner plate having a runner that extends to a ring runner around theshaft opening, the ring runner having openings that open to the passagesin the cavity plate when the runner plate is closed against the cavityplate, the ring runner including two semi-circular runners on oppositesides of the shaft opening, the semi-circular runners having theopenings therein; a key for each slot in the lamination stack, the keysprojecting into respective slots in the lamination stack and extendingthe length of the slots, the keys sized to provide thin wall flowregions before an outside diameter of the lamination stack to cause theplastic to start freezing off before it reaches the outside diameter ofthe lamination stack.
 201. The mold of claim 200 wherein the core plateincludes a pressure transducer port opening into the cavity of the moldin proximity to the commutator of the armature when the armature isreceived in the mold cavity.
 202. A two-plate mold for use in moldingplastic around an armature for an electric motor, the armature having ashaft with a lamination stack and an armature affixed to the shaft, theimprovement comprising the mold having a plurality of overflow tabcavities, each overflow tab cavity coupled to a mold cavity by a gatethat opens proximate to the commutator of the armature when the armatureis received in the mold cavity, each gate sized so that as moldingpressure builds up in the mold cavity, the plastic flows into theoverflow tab cavities before flashing over the commutator of thearmature.
 203. The mold of claim 202 wherein the overflow tab cavitiesare sized so that when they are full and molding pressure continues tobuild up in the mold cavity, the plastic has begun to freeze off in thearea of the commutator.
 204. A method of forming an armature for anelectric motor, comprising: placing a commutator and a lamination stackon an armature shaft; winding magnet wires in slots in the laminationstack to form coils; attaching ends of the magnet wires to thecommutator; placing the armature in a cavity of a core plate of a threeplate mold in an injection molding machine commutator first; locatingthe armature in the mold cavity by keys of the mold that project intothe slots, the keys extending the length of the slots; closing a cavityplate against the core plate and closing a runner plate against thecavity plate, the shaft of the armature extending through the cavityplate and a shaft opening in the runner plate; injecting thermallyconductive plastic into the mold cavity through a ring runner in therunner plate, through drop passages in the cavity plate and throughgates at the end of the drop passages that open to the mold cavity, thegates located in spaced relation to and between adjacent slots in thelamination stack so that each gate directs plastic into two adjacentslots in the lamination stack; freezing off the plastic before itreaches an outside diameter of the lamination stack by a thin wall flowregion before the outside diameter of the lamination stack provided bythe keys being sized to provide the thin wall flow region.
 205. A methodof forming an armature for an electric motor, comprising: placing acommutator and a lamination stack on an armature shaft; winding magnetwires in slots in the lamination stack to form coils; attaching ends ofthe magnet wires to the commutator; placing the armature in a cavity ofa two-plate mold; and injecting thermally conductive plastic into themold cavity and having the plastic flow into overflow cavities in thecavity plate of the mold before flashing over the commutator as moldingpressure builds up in the mold cavity.
 206. The method of claim 205 andfurther including having the plastic freeze off in the area of thecommutator by the time that the overflow tab cavities are full andmolding pressure continues to build up in the mold cavity.
 207. Anarmature for an electric motor, comprising: a lamination stack havingslots therein; an armature shaft extending coaxially through thelamination stack; a plurality of magnet wires wound in the slots of thelamination stack; a commutator disposed on the armature shaft to whichends of the magnet wires are electrically coupled; plastic at leastpartially encasing the magnet wires with at least one balancing featureformed from the plastic.
 208. The armature of claim 207 wherein thebalancing feature includes a layer of the plastic from which plastic canbe removed during dynamic balancing of the armature to balance thearmature.
 209. The armature of claim 208 wherein the layer of plasticincludes at least one balancing ring molded adjacent an axial side ofthe lamination stack.
 210. The armature of claim 208 wherein the layerof plastic includes balancing rings molded adjacent axial sides of thelamination stack.
 211. The armature of claim 210 wherein the plastic isthermally conductive plastic.
 212. The armature of claim 207 wherein theplastic is thermally conductive plastic.
 213. The armature of claim 207wherein the balancing feature includes a member having pockets thereinfor receiving weights.
 214. The armature of claim 207 wherein thebalancing feature includes at least one balancing ring molded adjacentan axial side of the lamination stack, the balancing ring including atleast one pocket therein for receiving a weight.
 215. The armature ofclaim 212 wherein the balancing ring includes a plurality of pocketstherein.
 216. The armature of claim 207 wherein the balancing featureincludes a plurality of balancing rings molded adjacent axial sides ofthe lamination stack, the balancing rings including a plurality ofpockets therein for receiving weights.
 217. The armature of claim 216wherein the plastic is thermally conductive plastic.
 218. An armaturefor an electric motor, comprising: lamination stack having slotstherein; an armature shaft extending coaxially through the laminationstack; a plurality of magnet wires wound in the slots of the laminationstack; a commutator disposed on the armature shaft to which ends of themagnet wires are electrically coupled; plastic at least partiallyencasing the magnet wires and forming a plurality of balancing ringsadjacent axial sides of the lamination stack.
 219. The armature of claim218 wherein the balancing rings include plastic that can be removedduring dynamic balancing of the armature to balance it.
 220. Thearmature of claim 218 wherein the balancing rings include a plurality ofpockets for receiving weights.
 221. A method of forming and balancing anarmature, comprising: securing a lamination stack having slots thereinon an armature shaft; securing a commutator on one end of the armatureshaft; winding magnet wires in the slots in the lamination stack andsecuring ends of the magnet wires to the commutator; molding plastic toat least partially encase the magnet wires in the plastic and forming abalancing feature; and removing plastic from at least one of thebalancing rings to balance the armature during dynamic balancing of thearmature.
 222. A method of forming and balancing an armature,comprising: securing a lamination stack having slots therein on anarmature shaft; securing a commutator on one end of the armature shaft;winding magnet wires in the slots in the lamination stack and securingends of the magnet wires to the commutator; molding plastic to at leastpartially encase the magnet wires in the plastic and forming balancingrings adjacent axial sides of the lamination stack; and removing plasticfrom at least one of the balancing rings to balance the armature duringdynamic balancing of the armature.
 223. A method of forming andbalancing an armature, comprising: securing a lamination stack havingslots therein on an armature shaft; securing a commutator on one end ofthe armature shaft; winding magnet wires in the slots in the laminationstack and securing ends of the magnet wires to the commutator; moldingplastic to at least partially encase the magnet wires in the plastic andforming a balancing feature having at least one pocket therein; andplacing a weight in the pocket to balance the armature during dynamicbalancing of the armature.
 224. A method of forming and balancing anarmature, comprising: securing a lamination stack having slots thereinon an armature shaft; securing a commutator on one end of the armatureshaft; winding magnet wires in the slots in the lamination stack andsecuring ends of the magnet wires to the commutator; molding plastic toat least partially encase the magnet wires in the plastic and formingbalancing rings adjacent axial sides of the lamination stack, thebalancing rings having pockets therein; and placing at least one weightin at least one pocket of at least one of the balancing rings to balancethe armature during dynamic balancing of the armature.
 225. A method forforming an armature for an electric motor, comprising: placing anelectrically insulative sleeve on an armature shaft; securing alamination stack having slots therein on the armature shaft; securing acommutator on one end of the armature shaft; winding magnet wires in theslots in the lamination stack and securing ends of the magnet wires tothe commutator; and molding thermally conductive plastic to at leastpartially encase the magnet wires in plastic, the thermally conductiveplastic having a base polymer that is a blend of at least two polymers.226. The method of claim 225 wherein the base polymer is a blend of atleast two of nylon, PPS, PPA and LCP.
 227. The method of claim 225wherein the base polymer is a blend of PPS and at least one of nylon,PPA and LCP.
 228. The method of claim 225 wherein the base polymer is ablend of about ninety percent PPS and about ten percent LCP.
 229. Anarmature for an electric motor, comprising: a lamination stack havingslots therein; an armature shaft extending coaxially through thelamination stack; a plurality of magnet wires wound in the slots of thelamination stack; a commutator disposed on the armature shaft to whichends of the magnet wires are electrically coupled; and thermallyconductive plastic at least partially encasing the magnet wires, thethermally conductive plastic having a base polymer that is a blend of atleast two polymers.
 230. The method of claim 229 wherein the basepolymer is a blend of at least two of nylon, PPS, PPA and LCP.
 231. Themethod of claim 229 wherein the base polymer is a blend of PPS and atleast one of nylon, PPA and LCP.